feat(simulation): integrate observer visibility query (#112)

Replace unfiltered generate_snapshot with compute_observer_snapshot
that combines shadowcasting + vision cone to send only visible
entities and tiles. Enforces information asymmetry (D-011): NPCs
behind walls or in the blind spot are excluded from the snapshot.

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

server/src/bridge/mod.rs

@@ -59,7 +59,9 @@ impl BridgeResource {
     }
 }
 
-/// Generate ObserverSnapshot from ECS state
+/// Generate ObserverSnapshot v2 from ECS state.
+/// Pre-visibility version: sends ALL entities (no LOS filtering yet).
+/// Will be replaced by perception::observer::compute_observer_snapshot in #112.
 pub fn generate_snapshot(
     time: Res<crate::simulation::time::SimulationTime>,
     entities: Query<(
@@ -86,16 +88,29 @@ pub fn generate_snapshot(
             y,
             z,
             kind,
+            visibility: VisibilitySector::Forward,
         });
     }
+
+    let game_time = GameTime {
+        day: time.day(),
+        time_of_day: time.time_of_day_minutes(),
+        day_phase: time.day_phase(),
+        paused: time.paused,
+    };
+
     tracing::trace!(
         "generate_snapshot: tick={}, entities={}",
         time.tick,
         visible.len()
     );
     buffer.snapshot = Some(ObserverSnapshot {
+        version: 2,
         tick: time.tick,
+        game_time,
+        player_facing: FacingDirection::default(),
         entities: visible,
+        visible_tiles: Vec::new(), // Empty until #112 adds LOS filtering
     });
 }
 
@@ -159,10 +174,11 @@ impl Plugin for BridgePlugin {
                 Update,
                 (
                     receive_bridge_inputs.before(crate::simulation::input::process_player_input),
-                    generate_snapshot
+                    crate::perception::observer::compute_observer_snapshot
                         .after(crate::simulation::movement::validate_movement)
                         .before(crate::simulation::time::advance_tick),
-                    send_bridge_snapshot.after(generate_snapshot),
+                    send_bridge_snapshot
+                        .after(crate::perception::observer::compute_observer_snapshot),
                 ),
             );
         tracing::debug!("BridgePlugin initialized");