feat: add comprehensive recovery playbook and update documentation

- Added RECOVERY_PLAYBOOK.md with complete offline recovery guide
- Updated README.md to reference manual restore method
- Added RECOVERY_PLAYBOOK.md to project structure
- Removed test.pgp file

README.md

@@ -54,13 +54,24 @@ bun run dev
 3. Click "Backup" to encrypt and generate QR code
 4. Save/print QR code for offline storage
 
-**Restore Flow:**
+**Restore Flow (Web Interface):**
 
 1. Scan QR code or paste encrypted text
 2. Import PGP private key or enter password
 3. Click "Restore" to decrypt mnemonic
 4. Mnemonic auto-clears after 10 seconds
 
+**Offline/Manual Restore:**
+
+For airgapped recovery without the web interface, use the command-line method documented in [RECOVERY_PLAYBOOK.md](RECOVERY_PLAYBOOK.md):
+
+1. Extract Base45 payload from SEEDPGP1 frame
+2. Decode Base45 to PGP binary
+3. Decrypt with GPG using private key or password
+4. Parse JSON output to recover mnemonic
+
+See [RECOVERY_PLAYBOOK.md](RECOVERY_PLAYBOOK.md) for complete step-by-step instructions.
+
 ### API Usage
 
 ```typescript
@@ -293,6 +304,7 @@ seedpgp-web/
 ├── package.json
 ├── vite.config.ts                  # Vite configuration
 ├── GEMINI.md                       # AI agent project brief
+├── RECOVERY_PLAYBOOK.md            # Offline recovery guide
 └── README.md                       # This file
 ```