Refactor: Remove audio processing and game state management modules

src/server-deno/application/mod.ts

@@ -0,0 +1,7 @@
+/**
+ * Application layer exports
+ */
+export { TrackService } from './TrackService.ts';
+export { RoomService } from './RoomService.ts';
+export { GameService } from './GameService.ts';
+export { AnswerCheckService } from './AnswerCheckService.ts';