feat: add narrative page turn audio cue

src/game/audio/SoundDirector.ts

@@ -57,7 +57,7 @@ export type MusicDuckOptions = {
   releaseMs?: number;
 };
 
-type SemanticCueGroup = 'turn' | 'operation' | 'objective';
+type SemanticCueGroup = 'turn' | 'operation' | 'objective' | 'narrative';
 
 type MusicDuckState = {
   multiplier: number;
@@ -102,7 +102,8 @@ export class SoundDirector {
   private readonly semanticCueCooldownMs: Record<SemanticCueGroup, number> = {
     turn: 900,
     operation: 650,
-    objective: 1200
+    objective: 1200,
+    narrative: 220
   };
   private readonly semanticCuePlayedAt = new Map<SemanticCueGroup, number>();
   private lastPlayedSemanticCue?: { group: SemanticCueGroup; key: string; at: number };
@@ -434,6 +435,13 @@ export class SoundDirector {
     });
   }
 
+  playStoryAdvanceCue() {
+    return this.playSemanticCue('narrative', 'story-page-turn', {
+      volume: 0.15,
+      stopAfterMs: 1100
+    });
+  }
+
   playStrategyPulse() {
     this.playEffect('strategy-cast', { volume: 0.44, rate: 0.96, stopAfterMs: 960 });
     this.playTone(460, 0.08, 0.012, 'sine');
@@ -500,7 +508,7 @@ export class SoundDirector {
   private playSemanticCue(
     group: SemanticCueGroup,
     key: string,
-    options: PlayEffectOptions & { duck: MusicDuckOptions }
+    options: PlayEffectOptions & { duck?: MusicDuckOptions }
   ) {
     if (!this.started || this.muted || !this.effectTracks[key]) {
       return false;
@@ -519,7 +527,9 @@ export class SoundDirector {
       return false;
     }
 
-    this.duckMusic(options.duck);
+    if (options.duck) {
+      this.duckMusic(options.duck);
+    }
     const played = this.playEffect(key, options);
     if (played) {
       this.semanticCuePlayedAt.set(group, now);