feat: fix CompactSeedQR binary QR code scanning with jsQR library

- Replace BarcodeDetector with jsQR for raw binary byte access
- BarcodeDetector forced UTF-8 decoding which corrupted binary data
- jsQR's binaryData property preserves raw bytes without text conversion
- Fix regex bug: use single backslash \x00 instead of \x00 for binary detection
- Add debug logging for scan data inspection
- QR generation already worked (Krux-compatible), only scanning was broken

Resolves binary QR code scanning for 12/24-word CompactSeedQR format.
Tested with Krux device - full bidirectional compatibility confirmed.

debug_krux.py

@@ -0,0 +1,71 @@
+#
+# This is a debug script to trace the Krux decryption process.
+# It has been modified to be self-contained and avoid MicroPython-specific libraries.
+#
+import sys
+
+# Add the source directory to the path to allow imports
+sys.path.append('REFERENCE/krux/src')
+
+from krux.baseconv import pure_python_base_decode
+
+def unwrap_standalone(kef_bytes):
+    """A self-contained version of kef.unwrap for debugging."""
+    try:
+        len_id = kef_bytes[0]
+        if not (0 <= len_id <= 252):
+             raise ValueError(f"Invalid label length: {len_id}")
+        if len(kef_bytes) < (1 + len_id + 4):
+            raise ValueError("KEF bytes too short for header")
+
+        id_ = kef_bytes[1 : 1 + len_id]
+        version = kef_bytes[1 + len_id]
+        kef_iterations = int.from_bytes(kef_bytes[2 + len_id : 5 + len_id], "big")
+        
+        if kef_iterations <= 10000:
+            iterations = kef_iterations * 10000
+        else:
+            iterations = kef_iterations
+            
+        payload = kef_bytes[len_id + 5 :]
+        return (id_, version, iterations, payload)
+    except Exception as e:
+        raise ValueError(f"Failed to unwrap KEF envelope: {e}")
+
+
+def debug_krux_decryption():
+    # Test case from the user
+    base43_string = "1334+HGXM$F8PPOIRNHX0.R*:SBMHK$X88LX$*/Y417R/6S1ZQOB2LHM-L+4T1YQVU:B*CKGXONP7:Y/R-B*:$R8FK"
+
+    print("--- Krux Decryption Debug (Phase 1: Decoding & Unwrapping) ---")
+    print(f"Input Base43: {base43_string}\n")
+
+    # Step 1: Base43 Decode
+    try:
+        kef_envelope_bytes = pure_python_base_decode(base43_string, 43)
+        print(f"[OK] Step 1: Base43 Decoded (KEF Envelope Hex):")
+        print(kef_envelope_bytes.hex())
+        print("-" * 20)
+    except Exception as e:
+        print(f"[FAIL] Step 1: Base43 Decoding failed: {e}")
+        return
+
+    # Step 2: Unwrap KEF Envelope
+    try:
+        label_bytes, version, iterations, payload = unwrap_standalone(kef_envelope_bytes)
+        label = label_bytes.decode('utf-8', errors='ignore')
+        print(f"[OK] Step 2: KEF Unwrapped")
+        print(f"  - Label: '{label}'")
+        print(f"  - Version: {version}")
+        print(f"  - Iterations: {iterations}")
+        print(f"  - Payload (Hex): {payload.hex()}")
+        print("-" * 20)
+        print("\n--- DEBUGGING COMPLETE ---")
+        print("Please paste this entire output for analysis.")
+
+    except Exception as e:
+        print(f"[FAIL] Step 2: KEF Unwrapping failed: {e}")
+        return
+
+if __name__ == '__main__':
+    debug_krux_decryption()