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/bridge/text_renderer.rs

@@ -192,6 +192,7 @@ fn sector_label(sector: VisibilitySector) -> &'static str {
     match sector {
         VisibilitySector::Forward => "Forward",
         VisibilitySector::Peripheral => "Periph",
+        VisibilitySector::BoundaryWall => "BndWall",
     }
 }
 
@@ -316,6 +317,7 @@ mod tests {
             triangle_crisis_events: vec![],
             state_hash: None,
             sim_errors: vec![],
+            debug_response: None,
         }
     }
 
@@ -454,6 +456,7 @@ mod tests {
             triangle_crisis_events: vec![],
             state_hash: None,
             sim_errors: vec![],
+            debug_response: None,
         };
         let text = format_snapshot_text(&snap);
         assert!(text.contains("Tick 0"));