feat(identity-wallet): register check_identity_status Tauri IPC command
Adds Tauri IPC command that wires PlcMonitor to the frontend:
- Takes AppState with configured PdsClient
- Creates PlcMonitor with PdsClient reference
- Calls check_all() to monitor all managed identities
- Returns list of IdentityStatus with unauthorized changes
- Serializes errors as { code, message } for frontend error handling
Uses lifetime generics to hold PdsClient reference since reqwest::Client
does not implement Clone.