feat(v1.2.1): add security monitoring components

- Add Storage Indicator (browser localStorage/sessionStorage monitor)
- Add Security Warnings (educational panel on JS limitations)
- Add Clipboard Tracker (copy event detection with clear function)
- Add data-sensitive attributes to sensitive fields

Security Features:
- Real-time storage monitoring with sensitive data highlighting
- Clipboard activity tracking with character count
- System clipboard clearing functionality
- Collapsible floating widgets (non-intrusive)
- Auto-refresh storage display every 2s
- Educational warnings about GC, string immutability, etc.

UI/UX:
- Floating widgets: Storage (bottom-right), Warnings (bottom-left), Clipboard (bottom-right stacked)
- Color-coded alerts (red=sensitive, orange=activity, yellow=warnings)
- Responsive and clean design with TailwindCSS

src/components/ClipboardTracker.tsx

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+import { useState, useEffect } from 'react';
+
+interface ClipboardEvent {
+    timestamp: Date;
+    field: string;
+    length: number; // Show length without storing actual content
+}
+
+export const ClipboardTracker = () => {
+    const [events, setEvents] = useState<ClipboardEvent[]>([]);
+    const [isExpanded, setIsExpanded] = useState(false);
+
+    useEffect(() => {
+        const handleCopy = (e: ClipboardEvent & Event) => {
+            const target = e.target as HTMLElement;
+
+            // Get selection to measure length
+            const selection = window.getSelection()?.toString() || '';
+            const length = selection.length;
+
+            if (length === 0) return; // Nothing copied
+
+            // Detect field name
+            let field = 'Unknown field';
+
+            if (target.tagName === 'TEXTAREA' || target.tagName === 'INPUT') {
+                // Try multiple ways to identify the field
+                field =
+                    target.getAttribute('aria-label') ||
+                    target.getAttribute('name') ||
+                    target.getAttribute('id') ||
+                    (target as HTMLInputElement).type ||
+                    target.tagName.toLowerCase();
+
+                // Check parent labels
+                const label = target.closest('label') ||
+                    document.querySelector(`label[for="${target.id}"]`);
+                if (label) {
+                    field = label.textContent?.trim() || field;
+                }
+
+                // Check for data-sensitive attribute
+                const sensitiveAttr = target.getAttribute('data-sensitive') ||
+                    target.closest('[data-sensitive]')?.getAttribute('data-sensitive');
+                if (sensitiveAttr) {
+                    field = sensitiveAttr;
+                }
+
+                // Detect if it looks like sensitive data
+                const isSensitive = /mnemonic|seed|key|private|password|secret/i.test(
+                    target.className + ' ' + field + ' ' + (target.getAttribute('placeholder') || '')
+                );
+
+                if (isSensitive && field === target.tagName.toLowerCase()) {
+                    // Try to guess from placeholder
+                    const placeholder = target.getAttribute('placeholder');
+                    if (placeholder) {
+                        field = placeholder.substring(0, 40) + '...';
+                    }
+                }
+            }
+
+            setEvents(prev => [
+                { timestamp: new Date(), field, length },
+                ...prev.slice(0, 9) // Keep last 10 events
+            ]);
+
+            // Auto-expand on first copy
+            if (events.length === 0) {
+                setIsExpanded(true);
+            }
+        };
+
+        document.addEventListener('copy', handleCopy as EventListener);
+        return () => document.removeEventListener('copy', handleCopy as EventListener);
+    }, [events.length]);
+
+    const clearClipboard = async () => {
+        try {
+            // Actually clear the system clipboard
+            await navigator.clipboard.writeText('');
+
+            // Clear history
+            setEvents([]);
+
+            // Show success briefly
+            alert('✅ Clipboard cleared and history wiped');
+        } catch (err) {
+            // Fallback for browsers that don't support clipboard API
+            const dummy = document.createElement('textarea');
+            dummy.value = '';
+            document.body.appendChild(dummy);
+            dummy.select();
+            document.execCommand('copy');
+            document.body.removeChild(dummy);
+
+            setEvents([]);
+            alert('✅ History cleared (clipboard may require manual clearing)');
+        }
+    };
+
+    return (
+        <div className="fixed bottom-24 right-4 z-50 max-w-sm">
+            <div className={`rounded-lg shadow-lg border-2 transition-all ${events.length > 0
+                ? 'bg-orange-50 border-orange-400'
+                : 'bg-gray-50 border-gray-300'
+                }`}>
+
+                {/* Header */}
+                <div
+                    className={`px-4 py-3 cursor-pointer flex items-center justify-between rounded-t-lg transition-colors ${events.length > 0 ? 'hover:bg-orange-100' : 'hover:bg-gray-100'
+                        }`}
+                    onClick={() => setIsExpanded(!isExpanded)}
+                >
+                    <div className="flex items-center gap-2">
+                        <span className="text-lg">📋</span>
+                        <span className="font-semibold text-sm text-gray-700">Clipboard Activity</span>
+                    </div>
+
+                    <div className="flex items-center gap-2">
+                        {events.length > 0 && (
+                            <span className="text-xs bg-orange-500 text-white px-2 py-0.5 rounded-full font-medium">
+                                {events.length}
+                            </span>
+                        )}
+                        <span className="text-gray-400 text-sm">{isExpanded ? '▼' : '▶'}</span>
+                    </div>
+                </div>
+
+                {/* Expanded Content */}
+                {isExpanded && (
+                    <div className="p-4 border-t border-gray-300">
+                        {events.length > 0 && (
+                            <div className="mb-3 bg-orange-100 border border-orange-300 rounded-md p-3 text-xs text-orange-900">
+                                <strong>⚠️ Clipboard Warning:</strong> Copied data is accessible to other apps,
+                                browser tabs, and extensions. Clear clipboard after use.
+                            </div>
+                        )}
+
+                        {events.length > 0 ? (
+                            <>
+                                <div className="space-y-2 mb-3 max-h-64 overflow-y-auto">
+                                    {events.map((event, idx) => (
+                                        <div
+                                            key={idx}
+                                            className="bg-white border border-orange-200 rounded-md p-2 text-xs"
+                                        >
+                                            <div className="flex justify-between items-start gap-2 mb-1">
+                                                <span className="font-semibold text-orange-900 break-all">
+                                                    {event.field}
+                                                </span>
+                                                <span className="text-gray-400 text-[10px] whitespace-nowrap">
+                                                    {event.timestamp.toLocaleTimeString()}
+                                                </span>
+                                            </div>
+                                            <div className="text-gray-600 text-[10px]">
+                                                Copied {event.length} character{event.length !== 1 ? 's' : ''}
+                                            </div>
+                                        </div>
+                                    ))}
+                                </div>
+
+                                <button
+                                    onClick={(e) => {
+                                        e.stopPropagation(); // Prevent collapse toggle
+                                        clearClipboard();
+                                    }}
+                                    className="w-full text-xs py-2 px-3 bg-orange-600 hover:bg-orange-700 text-white rounded-md font-medium transition-colors"
+                                >
+                                    🗑️ Clear Clipboard & History
+                                </button>
+                            </>
+                        ) : (
+                            <div className="text-center py-4">
+                                <div className="text-3xl mb-2">✅</div>
+                                <p className="text-xs text-gray-500">No clipboard activity detected</p>
+                            </div>
+                        )}
+                    </div>
+                )}
+            </div>
+        </div>
+    );
+};

src/components/SecurityWarnings.tsx

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+import { useState } from 'react';
+
+export const SecurityWarnings = () => {
+    const [isExpanded, setIsExpanded] = useState(false);
+
+    return (
+        <div className="fixed bottom-4 left-4 z-50 max-w-sm">
+            <div className="bg-yellow-50 border-2 border-yellow-400 rounded-lg shadow-lg">
+
+                {/* Header */}
+                <div
+                    className="px-4 py-3 cursor-pointer flex items-center justify-between hover:bg-yellow-100 transition-colors rounded-t-lg"
+                    onClick={() => setIsExpanded(!isExpanded)}
+                >
+                    <div className="flex items-center gap-2">
+                        <span className="text-lg">⚠️</span>
+                        <span className="font-semibold text-sm text-yellow-900">Security Limitations</span>
+                    </div>
+                    <span className="text-yellow-600 text-sm">{isExpanded ? '▼' : '▶'}</span>
+                </div>
+
+                {/* Expanded Content */}
+                {isExpanded && (
+                    <div className="px-4 py-3 border-t border-yellow-300 space-y-3 max-h-96 overflow-y-auto">
+
+                        <Warning
+                            icon="🧵"
+                            title="JavaScript Strings are Immutable"
+                            description="Strings cannot be overwritten in memory. Copies persist until garbage collection runs (timing unpredictable)."
+                        />
+
+                        <Warning
+                            icon="🗑️"
+                            title="No Guaranteed Memory Wiping"
+                            description="JavaScript has no secure memory clearing. Sensitive data may linger in RAM until GC or browser restart."
+                        />
+
+                        <Warning
+                            icon="📋"
+                            title="Clipboard Exposure"
+                            description="Copied data is accessible to other tabs/apps. Browser extensions can read clipboard contents."
+                        />
+
+                        <Warning
+                            icon="💾"
+                            title="Browser Storage Persistence"
+                            description="localStorage survives browser restart. sessionStorage survives page refresh. Both readable by any script on this domain."
+                        />
+
+                        <Warning
+                            icon="🔍"
+                            title="DevTools Access"
+                            description="All app state, memory, and storage visible in browser DevTools. Never use on untrusted devices."
+                        />
+
+                        <Warning
+                            icon="🌐"
+                            title="Network Risks (When Online)"
+                            description="If hosted online: DNS, HTTPS, CDN, and browser can see usage patterns. Use offline/local for maximum security."
+                        />
+
+                        <div className="pt-2 border-t border-yellow-300 text-xs text-yellow-800">
+                            <strong>Recommendation:</strong> Use this tool on a dedicated offline device.
+                            Clear browser data after each use. Never use on shared/public computers.
+                        </div>
+                    </div>
+                )}
+            </div>
+        </div>
+    );
+};
+
+const Warning = ({ icon, title, description }: { icon: string; title: string; description: string }) => (
+    <div className="flex gap-2 text-xs">
+        <span className="text-base flex-shrink-0">{icon}</span>
+        <div>
+            <div className="font-semibold text-yellow-900 mb-0.5">{title}</div>
+            <div className="text-yellow-800 leading-relaxed">{description}</div>
+        </div>
+    </div>
+);

src/components/StorageIndicator.tsx

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+import { useState, useEffect } from 'react';
+
+interface StorageItem {
+    key: string;
+    value: string;
+    size: number;
+    isSensitive: boolean;
+}
+
+export const StorageIndicator = () => {
+    const [localItems, setLocalItems] = useState<StorageItem[]>([]);
+    const [sessionItems, setSessionItems] = useState<StorageItem[]>([]);
+    const [isExpanded, setIsExpanded] = useState(false);
+
+    const SENSITIVE_PATTERNS = ['key', 'mnemonic', 'seed', 'private', 'secret', 'pgp', 'password'];
+
+    const isSensitiveKey = (key: string): boolean => {
+        const lowerKey = key.toLowerCase();
+        return SENSITIVE_PATTERNS.some(pattern => lowerKey.includes(pattern));
+    };
+
+    const getStorageItems = (storage: Storage): StorageItem[] => {
+        const items: StorageItem[] = [];
+        for (let i = 0; i < storage.length; i++) {
+            const key = storage.key(i);
+            if (key) {
+                const value = storage.getItem(key) || '';
+                items.push({
+                    key,
+                    value: value.substring(0, 50) + (value.length > 50 ? '...' : ''),
+                    size: new Blob([value]).size,
+                    isSensitive: isSensitiveKey(key)
+                });
+            }
+        }
+        return items.sort((a, b) => (b.isSensitive ? 1 : 0) - (a.isSensitive ? 1 : 0));
+    };
+
+    const refreshStorage = () => {
+        setLocalItems(getStorageItems(localStorage));
+        setSessionItems(getStorageItems(sessionStorage));
+    };
+
+    useEffect(() => {
+        refreshStorage();
+        const interval = setInterval(refreshStorage, 2000);
+        return () => clearInterval(interval);
+    }, []);
+
+    const totalItems = localItems.length + sessionItems.length;
+    const sensitiveCount = [...localItems, ...sessionItems].filter(i => i.isSensitive).length;
+
+    return (
+        <div className="fixed bottom-4 right-4 z-50 max-w-md">
+            <div className={`bg-white rounded-lg shadow-lg border-2 ${sensitiveCount > 0 ? 'border-red-400' : 'border-gray-300'
+                } transition-all duration-200`}>
+
+                {/* Header Bar */}
+                <div
+                    className={`px-4 py-3 rounded-t-lg cursor-pointer flex items-center justify-between ${sensitiveCount > 0 ? 'bg-red-50' : 'bg-gray-50'
+                        } hover:opacity-90 transition-opacity`}
+                    onClick={() => setIsExpanded(!isExpanded)}
+                >
+                    <div className="flex items-center gap-2">
+                        <span className="text-lg">🗄️</span>
+                        <span className="font-semibold text-sm text-gray-700">Storage Monitor</span>
+                    </div>
+
+                    <div className="flex items-center gap-2">
+                        {sensitiveCount > 0 && (
+                            <span className="text-xs bg-red-500 text-white px-2 py-0.5 rounded-full font-medium">
+                                {sensitiveCount}⚠️
+                            </span>
+                        )}
+                        <span className={`text-xs px-2 py-0.5 rounded-full font-medium ${totalItems > 0 ? 'bg-blue-100 text-blue-700' : 'bg-green-100 text-green-700'
+                            }`}>
+                            {totalItems === 0 ? '✓ Empty' : `${totalItems} item${totalItems !== 1 ? 's' : ''}`}
+                        </span>
+                        <span className="text-gray-400 text-sm">{isExpanded ? '▼' : '▶'}</span>
+                    </div>
+                </div>
+
+                {/* Expanded Content */}
+                {isExpanded && (
+                    <div className="p-4 max-h-96 overflow-y-auto">
+                        {sensitiveCount > 0 && (
+                            <div className="mb-3 bg-yellow-50 border border-yellow-300 rounded-md p-3 text-xs">
+                                <div className="flex items-start gap-2">
+                                    <span className="text-yellow-600 mt-0.5">⚠️</span>
+                                    <div className="text-yellow-800">
+                                        <strong>Security Notice:</strong> Sensitive data persists in browser storage
+                                        (survives refresh/restart). Clear manually if on shared device.
+                                    </div>
+                                </div>
+                            </div>
+                        )}
+
+                        <div className="space-y-3">
+                            <StorageSection title="localStorage" items={localItems} icon="💾" />
+                            <StorageSection title="sessionStorage" items={sessionItems} icon="⏱️" />
+                        </div>
+
+                        {totalItems === 0 && (
+                            <div className="text-center py-6">
+                                <div className="text-4xl mb-2">✅</div>
+                                <p className="text-sm text-gray-500">No data in browser storage</p>
+                            </div>
+                        )}
+                    </div>
+                )}
+            </div>
+        </div>
+    );
+};
+
+const StorageSection = ({ title, items, icon }: { title: string; items: StorageItem[]; icon: string }) => {
+    if (items.length === 0) return null;
+
+    return (
+        <div>
+            <h4 className="text-xs font-bold text-gray-500 mb-2 flex items-center gap-1">
+                <span>{icon}</span>
+                <span className="uppercase">{title}</span>
+                <span className="ml-auto text-gray-400 font-normal">({items.length})</span>
+            </h4>
+            <div className="space-y-2">
+                {items.map((item) => (
+                    <div
+                        key={item.key}
+                        className={`text-xs rounded-md border p-2 ${item.isSensitive
+                                ? 'bg-red-50 border-red-300'
+                                : 'bg-gray-50 border-gray-200'
+                            }`}
+                    >
+                        <div className="flex justify-between items-start gap-2 mb-1">
+                            <span className={`font-mono font-semibold text-[11px] break-all ${item.isSensitive ? 'text-red-700' : 'text-gray-700'
+                                }`}>
+                                {item.isSensitive && '🔴 '}{item.key}
+                            </span>
+                            <span className="text-gray-400 text-[10px] whitespace-nowrap">{item.size}B</span>
+                        </div>
+                        <div className="text-gray-500 font-mono text-[10px] break-all leading-relaxed opacity-70">
+                            {item.value}
+                        </div>
+                    </div>
+                ))}
+            </div>
+        </div>
+    );
+};