feat(identity-wallet): add claim_state to AppState
- Add claim_state field to AppState using tokio::sync::Mutex<Option<ClaimState>>
- Initialize claim_state in AppState::new() to None
- tokio::sync::Mutex allows holding lock across .await points (necessary for async claim commands)
- claim_state is set by resolve_identity and used by subsequent claim flow commands
- Verified: cargo check passes without errors