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/bridge/text_renderer.rs

@@ -299,6 +299,7 @@ mod tests {
             dialogue_response: None,
             blocked_entities: vec![],
             scan_events: vec![],
+            sound_events: vec![],
         }
     }
 
@@ -422,6 +423,7 @@ mod tests {
             dialogue_response: None,
             blocked_entities: vec![],
             scan_events: vec![],
+            sound_events: vec![],
         };
         let text = format_snapshot_text(&snap);
         assert!(text.contains("Tick 0"));

server/src/bridge/types.rs

@@ -15,7 +15,7 @@ pub use crate::simulation::time::{DayPhase, TickRate};
 /// negotiation is unnecessary. Client should reject snapshots with version !=
 /// PROTOCOL_VERSION. New fields use #[serde(default)] only during the migration
 /// period, then the default is removed once both sides are updated.
-pub const PROTOCOL_VERSION: u8 = 9;
+pub const PROTOCOL_VERSION: u8 = 10;
 
 /// The ONLY data structure crossing the client-server boundary (D-020)
 /// Contains all information visible to the observer at a given tick.
@@ -28,7 +28,7 @@ pub const PROTOCOL_VERSION: u8 = 9;
 /// v7 adds: pending_recognitions (#423, D-060 cognitive delay).
 /// v8 adds: dialogue_response (#305, D-028 dialogue pipeline).
 /// v9 adds: blocked_entities (#514, debug field for LOS-blocked entities).
-/// Future fields: ambient sound events, HUD state (D-020 expansion).
+/// v10 adds: sound_events (#124, D-038 server sound event pipeline).
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ObserverSnapshot {
     /// Protocol version for forward compatibility. Current: 9.
@@ -79,6 +79,12 @@ pub struct ObserverSnapshot {
     /// Sorted ascending for deterministic output. Client can safely ignore.
     #[serde(default)]
     pub blocked_entities: Vec<u64>,
+    /// Sound events audible to the observer this tick (#124, D-038).
+    /// Filtered by D-018 range categories relative to player position.
+    /// Client AudioManager maps each event's kind to an audio asset.
+    /// Empty when no sounds are in range.
+    #[serde(default)]
+    pub sound_events: Vec<crate::simulation::sound::SoundEvent>,
 }
 
 /// Game time data for client display (D-031)