refactor: 将截图功能移到RHI模块的D3D12Screenshot类

engine/include/XCEngine/RHI/D3D12/D3D12Screenshot.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <d3d12.h>
+#include <string>
+
+namespace XCEngine {
+namespace RHI {
+
+class D3D12Screenshot {
+public:
+    static bool Capture(ID3D12Device* device, 
+                       ID3D12CommandQueue* commandQueue,
+                       ID3D12Resource* renderTarget,
+                       const char* filename,
+                       uint32_t width,
+                       uint32_t height);
+
+private:
+    static bool CopyToReadbackAndSave(ID3D12Device* device,
+                                      ID3D12CommandQueue* commandQueue,
+                                      ID3D12Resource* renderTarget,
+                                      const char* filename,
+                                      uint32_t width,
+                                      uint32_t height);
+};
+
+} // namespace RHI
+} // namespace XCEngine