docs: update memory and threading API docs

docs/api/threading/task-group/is-complete.md

@@ -0,0 +1,50 @@
+# TaskGroup::IsComplete
+
+```cpp
+bool IsComplete() const;
+```
+
+检查任务组中的所有任务是否已完成。
+
+**参数：** 无
+
+**返回：** 
+- `true` - 所有任务已完成（包括被取消的）
+- `false` - 仍有任务在执行或等待执行
+
+**线程安全：** ✅ 线程安全
+
+**示例：**
+
+```cpp
+#include "XCEngine/Threading/TaskGroup.h"
+#include "XCEngine/Threading/Task.h"
+#include <iostream>
+#include <chrono>
+
+using namespace XCEngine::Threading;
+
+int main() {
+    TaskGroup group;
+
+    group.AddTask([]() {
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        std::cout << "Task completed\n";
+    });
+
+    std::cout << "Immediately after AddTask, IsComplete: "
+              << (group.IsComplete() ? "true" : "false") << "\n";
+
+    group.Wait();
+
+    std::cout << "After Wait, IsComplete: "
+              << (group.IsComplete() ? "true" : "false") << "\n";
+
+    return 0;
+}
+```
+
+## 相关文档
+
+- [TaskGroup 总览](task-group.md) - 返回类总览
+- [GetProgress](get-progress.md) - 获取进度百分比