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/perception/observer/mod.rs

@@ -392,6 +392,9 @@ pub fn compute_observer_snapshot(
     // Consume pending save/load result for this tick (#553).
     let save_result = buffer.pending_save_result.take();
 
+    // Consume pending debug response for this tick (#580).
+    let debug_response = buffer.pending_debug_response.take();
+
     // Drain triangle crisis events (#250) and convert to wire format.
     // Drain triangle crisis events (#250) and filter role_assignments against
     // observer KG (D-010 principle 2: information boundaries are universal).
@@ -464,6 +467,7 @@ pub fn compute_observer_snapshot(
         triangle_crisis_events,
         state_hash,
         sim_errors,
+        debug_response,
     });
 }