WIP: Music callback

- 头几拍会抖动一下，导致对不上拍子

Assets/Scripts/OCES/Audio/HandWritten/AudioSystem.cs

@@ -26,6 +26,11 @@ namespace OCES.Audio
         // 公开接口
         // ─────────────────────────────────────────────
 
+        public event Action<uint> OnBeat;
+
+        public event Action<uint> OnBar;
+        public event Action<uint> OnGrid;
+
         public void Play(uint audioId, Action onPlay = null)
         {
             AudioObject obj = this.m_audioObjects.QueryById(audioId);
@@ -170,6 +175,10 @@ namespace OCES.Audio
                 musicPool,
                 ambiencePool);
             
+            this.m_musicSystem.OnBeat += id => this.OnBeat?.Invoke(id);
+            this.m_musicSystem.OnBar  += id => this.OnBar?.Invoke(id);
+            this.m_musicSystem.OnGrid += id => this.OnGrid?.Invoke(id);
+            
             // ── 注册 StateGroup ──
             EnumIds.RegisterAllGameState();