feat(simulation): add debug console server and LOS boundary wall margin

Debug and LOS tracks for Sprint 23 (#580, #584):

- DebugCommandKind enum with 10 variants (AdvanceTicks,
  SkipToContamination, TeleportToPosition, ForceContaminationActivate,
  InspectNpc, ListTriangles, ListPopulation, GetContaminationStatus,
  TeleportToLocation, ForceTriangleActivation)
- DebugResponsePayload on ObserverSnapshot, handle_debug_commands
  system gated by DebugEnabled resource
- PROTOCOL_VERSION bumped 17 → 18
- VisibilitySector::BoundaryWall variant — 1-tile wall margin beyond
  LOS boundary included in visible_tiles (not exploration/memory)
- compute_boundary_walls() pass in NaturalVision after FOV+cone

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

server/src/main.rs

@@ -300,6 +300,7 @@ fn send_panic_error(app: &App, panic_msg: &str) {
         save_result: None,
         triangle_crisis_events: vec![],
         state_hash: None,
+        debug_response: None,
         sim_errors: vec![SimError {
             kind: SimErrorKind::Panic,
             message: format!("Simulation panic: {}", panic_msg),