fix(scene): remove exit-gate flashes and sub-3 Hz-unsafe flickers

src/audio/drive-texture.ts

@@ -13,7 +13,7 @@ const PASS_BY_SECONDS = 1.6;
 
 export interface DriveTexture {
   setEnergy(sample: DriveEnergySample): void;
-  /** The exit gates going by: a filtered air sweep across the stereo field. */
+  /** Passing under the gantry: a filtered air sweep across the stereo field. */
   passBy?(): void;
   dispose(): void;
 }

src/audio/soundtrack-engine.ts

@@ -554,8 +554,8 @@ export function createSoundtrackEngine(
     },
     setChapterIntent(intent) {
       if (closed) return;
-      // The scene runs its exit gates on every chapter change; the drive
-      // texture answers with the air of the gates going by.
+      // Every chapter change passes under the overhead gantry; the drive
+      // texture answers with the air of the structure going by.
       if (intent.sectionId !== latestChapter.sectionId) driveTexture?.passBy?.();
       latestChapter = intent;
       mixer.setChapterIntent(intent);