feat(identity-wallet): implement submit_recovery_override and register Tauri commands
- Add submit_recovery_override function that POSTs signed operation to plc.directory
- Re-fetches audit log and DID document to update Keychain cache
- Add build_recovery_override_cmd Tauri command wrapper
- Add submit_recovery_override_cmd Tauri command wrapper
- Register both commands in generate_handler\! macro
- Add test for SignedRecoveryOp serialization with camelCase
- Verifies AC7.4: Recovery override submission to plc.directory