refactor: 将 tests/D3D12 的 CommandList 替换为 D3D12CommandList 类

- 将全局 ID3D12GraphicsCommandList 替换为 D3D12CommandList
- 更新初始化、Reset、Close 调用
- 修复 Initialize 中不应调用 Close() 的问题
- 测试通过，截图与 GT.ppm 完全匹配

engine/include/XCEngine/RHI/D3D12/D3D12CommandList.h

@@ -41,7 +41,7 @@ public:
     D3D12CommandList();
     ~D3D12CommandList();
 
-    bool Initialize(ID3D12Device* device, CommandQueueType type = CommandQueueType::Direct);
+    bool Initialize(ID3D12Device* device, CommandQueueType type = CommandQueueType::Direct, ID3D12CommandAllocator* allocator = nullptr);
     void Shutdown();
 
     void Reset(ID3D12CommandAllocator* allocator);

engine/src/RHI/D3D12CommandList.cpp

@@ -15,23 +15,13 @@ D3D12CommandList::~D3D12CommandList() {
     Shutdown();
 }
 
-bool D3D12CommandList::Initialize(ID3D12Device* device, CommandQueueType type) {
+bool D3D12CommandList::Initialize(ID3D12Device* device, CommandQueueType type, ID3D12CommandAllocator* allocator) {
     D3D12_COMMAND_LIST_TYPE listType = ToD3D12(type);
 
-    ComPtr<ID3D12CommandAllocator> tempAllocator;
-    HRESULT hResult = device->CreateCommandAllocator(
-        listType,
-        IID_PPV_ARGS(&tempAllocator)
-    );
-
-    if (FAILED(hResult)) {
-        return false;
-    }
-
-    hResult = device->CreateCommandList(
+    HRESULT hResult = device->CreateCommandList(
         0,
         listType,
-        tempAllocator.Get(),
+        allocator,
         nullptr,
         IID_PPV_ARGS(&m_commandList)
     );
@@ -42,7 +32,6 @@ bool D3D12CommandList::Initialize(ID3D12Device* device, CommandQueueType type) {
 
     m_type = type;
 
-    m_commandList->Close();
     return true;
 }