refactor(coroutine): 优化异步操作延续处理逻辑

- 使用while循环替代递归调用避免栈溢出风险
- 改进CAS操作的重试机制提高并发安全性
- 简化空值检查逻辑提升代码可读性
- 优化双重检查锁模式确保线程安全

GFramework.Core/coroutine/instructions/AsyncOperation.cs

@@ -27,6 +27,8 @@ public class AsyncOperation : IYieldInstruction, INotifyCompletion
     /// </summary>
     /// <param name="continuation">要执行的延续操作</param>
     public void OnCompleted(Action continuation)
+    {
+        while (true)
         {
             // 尝试添加延续
             var current = _continuation;
@@ -39,7 +41,7 @@ public class AsyncOperation : IYieldInstruction, INotifyCompletion
                     continuation();
                 else
                     // 重试
-                OnCompleted(continuation);
+                    continue;
 
                 return;
             }
@@ -48,7 +50,10 @@ public class AsyncOperation : IYieldInstruction, INotifyCompletion
             if (_completed)
             {
                 var cont = Interlocked.Exchange(ref _continuation, null);
-            if (cont != null) cont();
+                cont?.Invoke();
+            }
+
+            break;
         }
     }