docs: update memory and threading API docs

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

@@ -0,0 +1,35 @@
+# ProxyAllocator::GetTotalAllocated
+
+```cpp
+size_t GetTotalAllocated() const override;
+```
+
+获取累计分配的字节数。
+
+**参数：** 无
+
+**返回：** 累计分配的字节数
+
+**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");
+
+proxy.Allocate(100);
+proxy.Allocate(200);
+
+size_t totalAllocated = proxy.GetTotalAllocated();
+printf("Total allocated: %zu bytes\n", totalAllocated);
+```
+
+## 相关文档
+
+- [ProxyAllocator 总览](proxy-allocator.md) - 返回类总览