Add missing destructor documentation for PoolAllocator and ProxyAllocator

- Created docs/api/memory/pool-allocator/~pool-allocator.md documenting the destructor
- Created docs/api/memory/proxy-allocator/~proxy-allocator.md documenting the destructor
- Added ~ProxyAllocator entry to proxy-allocator.md overview table
- Verified link validation passes (no broken references)

docs/api/memory/proxy-allocator/~proxy-allocator.md

@@ -0,0 +1,37 @@
+# ProxyAllocator::~ProxyAllocator
+
+```cpp
+~ProxyAllocator() override;
+```
+
+销毁代理分配器。此析构函数不释放底层分配器，只清理代理分配器自身的统计信息（互斥锁等）。底层分配器由创建者负责管理。
+
+**参数：** 无
+
+**返回：** 无
+
+**注意：** 析构函数不释放底层分配器。如果需要释放底层分配器，应先调用 `Shutdown` 或显式销毁底层分配器。
+
+**示例：**
+
+```cpp
+#include <XCEngine/Memory/MemoryManager.h>
+#include <XCEngine/Memory/ProxyAllocator.h>
+
+{
+    MemoryManager::Get().Initialize();
+    IAllocator* sysAlloc = MemoryManager::Get().GetSystemAllocator();
+    
+    auto proxy = MemoryManager::Get().CreateProxyAllocator("TrackedAlloc");
+    proxy->Allocate(1024);
+    
+    // proxy 超出作用域时自动销毁
+    // 底层 sysAlloc 仍有效
+    
+    MemoryManager::Get().Shutdown();
+}
+```
+
+## 相关文档
+
+- [ProxyAllocator 总览](proxy-allocator.md) - 返回类总览