refactor(coroutine): 优化 WaitForAllCoroutines 实现逻辑

- 将字段初始化改为构造函数中赋值
- 添加 _isDone 字段缓存完成状态
- 在构造函数中预处理空列表情况
- 优化 Update 方法减少重复计算
- 简化 IsDone 属性实现
- 提升协程等待性能

GFramework.Core/coroutine/instructions/WaitForAllCoroutines.cs

@@ -5,23 +5,30 @@ namespace GFramework.Core.coroutine.instructions;
 /// <summary>
 ///     等待所有协程完成的等待指令
 /// </summary>
-public sealed class WaitForAllCoroutines(
-    CoroutineScheduler scheduler,
-    IReadOnlyList<CoroutineHandle> handles)
-    : IYieldInstruction
+public sealed class WaitForAllCoroutines : IYieldInstruction
 {
-    private readonly IReadOnlyList<CoroutineHandle> _handles =
-        handles ?? throw new ArgumentNullException(nameof(handles));
+    private readonly IReadOnlyList<CoroutineHandle> _handles;
+    private readonly CoroutineScheduler _scheduler;
+    private bool _isDone;
 
-    private readonly CoroutineScheduler _scheduler = scheduler ?? throw new ArgumentNullException(nameof(scheduler));
+    public WaitForAllCoroutines(
+        CoroutineScheduler scheduler,
+        IReadOnlyList<CoroutineHandle> handles)
+    {
+        _scheduler = scheduler ?? throw new ArgumentNullException(nameof(scheduler));
+        _handles = handles ?? throw new ArgumentNullException(nameof(handles));
+
+        // 空列表直接完成
+        _isDone = _handles.Count == 0;
+    }
 
     public void Update(double deltaTime)
     {
-        // 不需要做任何事
+        if (_isDone) return;
+
+        // 检查所有协程是否都已完成
+        _isDone = _handles.All(handle => !_scheduler.IsCoroutineAlive(handle));
     }
 
-    public bool IsDone
-    {
-        get { return _handles.All(handle => !_scheduler.IsCoroutineAlive(handle)); }
-    }
+    public bool IsDone => _isDone;
 }