chore(simulation): update tests and fixtures for Sprint 23

- Add debug_response: None to all ObserverSnapshot constructors in
  integration tests
- Bump PROTOCOL_VERSION assertion 17 → 18 in serialization tests
- Regenerate golden proof_room_tick_10.json (BoundaryWall tiles)
- Regenerate client msgpack fixtures for new snapshot fields
- Fix debug.rs resource optionality (Option<ResMut> for
  ContaminationActive/EventQueue)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/tests/error_handling.rs

@@ -295,6 +295,7 @@ fn snapshot_with_sim_errors_roundtrips() {
         save_result: None,
         triangle_crisis_events: vec![],
         state_hash: Some(0xDEADBEEF),
+        debug_response: None,
         sim_errors: vec![
             SimError {
                 kind: SimErrorKind::ProtocolError,