fix(client-screen): add 'horse' to musicTrack type

修复构建错误：musicTrack 类型缺少 'horse' 选项

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/client-screen/src/stores/admin.ts

@@ -66,7 +66,7 @@ export const useAdminStore = defineStore('admin', () => {
 
   // Music State
   const musicPlaying = ref(false);
-  const musicTrack = ref<'bgm' | 'lottery' | 'fanfare' | 'award' | 'none'>('none');
+  const musicTrack = ref<'bgm' | 'lottery' | 'fanfare' | 'award' | 'horse' | 'none'>('none');
 
   // UI State
   const pendingAction = ref<string | null>(null);