feat(simulation): sprint 12 server — tier system, sound events, KG access, line previewer

Implements 4 completed tickets + partial progress on 2 more:

- #93 Tier marker components (ActiveSim, BackgroundSim, StateSaved + TierPlugin)
- #138 Information tag schema (ObserverAccess enum in knowledge/types.rs)
- #124 Sound event system (SoundEventEmitter, SoundEventQueue, bridge wiring)
- #193 Line previewer CLI (line_preview binary with filter/explain/sequence modes)
- #94 Active tier simulation (in progress — With<ActiveSim> filters)
- #139 Component-level access control (in progress — filter_by_access)

Updates snapshot fixtures and test golden files for new sound_events field.

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

server/src/simulation/mod.rs

@@ -15,6 +15,7 @@ pub mod movement;
 pub mod path_follow;
 pub mod pathfinding;
 pub mod rng;
+pub mod sound;
 pub mod stance;
 pub mod tier;
 pub mod time;
@@ -25,11 +26,15 @@ pub struct SimulationPlugin;
 
 impl Plugin for SimulationPlugin {
     fn build(&self, app: &mut App) {
+        // Tier marker components (D-026) — must register before behavior systems
+        app.add_plugins(tier::TierPlugin);
+
         // Initialize core simulation resources
         app.init_resource::<time::SimulationTime>()
             .insert_resource(rng::SimRng::new(0))
             .init_resource::<input::InputQueue>()
             .init_resource::<crate::knowledge::EntityRegistry>()
+            .init_resource::<sound::SoundEventQueue>()
             .add_systems(
                 Update,
                 (
@@ -42,6 +47,9 @@ impl Plugin for SimulationPlugin {
                     contraband::check_contraband_scan
                         .after(movement::validate_movement)
                         .before(crate::perception::observer::compute_observer_snapshot),
+                    sound::collect_sound_events
+                        .after(movement::validate_movement)
+                        .before(crate::perception::observer::compute_observer_snapshot),
                     time::advance_tick.after(path_follow::cleanup_path_blocked),
                 ),
             );