docs: update memory and threading API docs

docs/api/memory/memorymanager/createproxyallocator.md

@@ -0,0 +1,36 @@
+# MemoryManager::CreateProxyAllocator
+
+```cpp
+std::unique_ptr<ProxyAllocator> CreateProxyAllocator(const char* name);
+```
+
+创建并返回一个新的 ProxyAllocator 实例，包装系统分配器并使用指定名称。返回的 `unique_ptr` 管理分配器生命周期。
+
+**参数：**
+- `name` - 代理分配器的名称
+
+**返回：** ProxyAllocator 的 unique_ptr
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include <XCEngine/Memory/MemoryManager.h>
+
+auto proxy = MemoryManager::Get().CreateProxyAllocator("FrameData");
+void* ptr = proxy->Allocate(1024);
+void* ptr2 = proxy->Allocate(512);
+
+const auto& stats = proxy->GetStats();
+printf("Peak: %zu bytes, Count: %zu\n",
+    stats.peakAllocated, stats.allocationCount);
+
+proxy->Free(ptr);
+proxy->Free(ptr2);
+```
+
+## 相关文档
+
+- [MemoryManager 总览](memorymanager.md) - 返回类总览
+- [ProxyAllocator](../proxy-allocator/proxy-allocator.md) - 代理分配器