docs: update memory and threading API docs

docs/api/memory/proxy-allocator/get-total-freed.md

@@ -0,0 +1,35 @@
+# ProxyAllocator::GetTotalFreed
+
+```cpp
+size_t GetTotalFreed() const override;
+```
+
+获取累计释放的字节数。
+
+**参数：** 无
+
+**返回：** 累计释放的字节数
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include <XCEngine/Memory/MemoryManager.h>
+#include <XCEngine/Memory/ProxyAllocator.h>
+
+IAllocator* sysAlloc = MemoryManager::Get().GetSystemAllocator();
+ProxyAllocator proxy(sysAlloc, "TrackedAlloc");
+
+void* p1 = proxy.Allocate(100);
+proxy.Free(p1);
+
+size_t totalFreed = proxy.GetTotalFreed();
+printf("Total freed: %zu bytes\n", totalFreed);
+```
+
+## 相关文档
+
+- [ProxyAllocator 总览](proxy-allocator.md) - 返回类总览