refactor: WaitForAlignment coroutine use BeatClock.cs insted of calculate independently.

Assets/Scripts/OCES/Audio/HandWritten/LongAudio/BeatClock.cs

@@ -26,7 +26,7 @@ namespace OCES.Audio
             this.m_onGrid = onGrid;
         }
 
-        public void Restart(MusicContainer container, float inheritedBpm, double dspTime)
+        internal void Restart(MusicContainer container, float inheritedBpm, double dspTime)
         {
             //Debug.Log($"[BeatClock] Restart called, container={container.Id}, bpm={container.Bpm}, inherited={inheritedBpm}");
             
@@ -63,6 +63,26 @@ namespace OCES.Audio
             this.m_beatCoroutine = this.m_barCoroutine = this.m_gridCoroutine = null;
         }
 
+        internal double GetNextDspTime(AlignMode mode)
+        {
+            double now = AudioSettings.dspTime;
+            
+            if (this.m_blendError || this.m_stopped)
+            {
+                return now;
+            }
+            
+            double elapsed = now - this.m_startDspTime;
+            double period = mode switch
+            {
+                AlignMode.Beat => this.m_secondsPerBeat,
+                AlignMode.Bar  => this.m_secondsPerBeat * this.m_beatsPerBar,
+                _              => this.m_secondsPerBeat,
+            };
+            long next = (long)(elapsed / period) + 1L;
+            return this.m_startDspTime + next * period;
+        }
+
         IEnumerator BeatCoroutine()
         {
             double elapsed = AudioSettings.dspTime - this.m_startDspTime;