refactor: Refactor OpenGL backend to use OpenGLEnums

Use centralized OpenGLEnums.h for enum conversion:
- Remove local ToGL* functions from OpenGLCommandList
- Replace with ToOpenGL() and ToOpenGLClearBuffer() from OpenGLEnums
- Simplify OpenGLTexture, OpenGLBuffer, OpenGLSampler, etc.

engine/include/XCEngine/RHI/OpenGL/OpenGLDevice.h

@@ -39,7 +39,7 @@ public:
     RHISwapChain* CreateSwapChain(const SwapChainDesc& desc) override;
     RHICommandList* CreateCommandList(const CommandListDesc& desc) override;
     RHICommandQueue* CreateCommandQueue(const CommandQueueDesc& desc) override;
-    RHIShader* CompileShader(const ShaderCompileDesc& desc) override;
+    RHIShader* CreateShader(const ShaderCompileDesc& desc) override;
     RHIPipelineState* CreatePipelineState(const GraphicsPipelineDesc& desc) override;
     RHIPipelineLayout* CreatePipelineLayout(const RHIPipelineLayoutDesc& desc) override;
     RHIFence* CreateFence(const FenceDesc& desc) override;

engine/include/XCEngine/RHI/OpenGL/OpenGLScreenshot.h

@@ -2,6 +2,7 @@
 
 #include <cstdint>
 #include <string>
+#include "../RHIScreenshot.h"
 
 namespace XCEngine {
 namespace RHI {
@@ -9,8 +10,11 @@ namespace RHI {
 class OpenGLSwapChain;
 class OpenGLDevice;
 
-class OpenGLScreenshot {
+class OpenGLScreenshot : public RHIScreenshot {
 public:
+    bool Capture(RHIDevice* device, RHISwapChain* swapChain, const char* filename) override;
+    void Shutdown() override {}
+
     static bool Capture(OpenGLDevice& device,
                         OpenGLSwapChain& swapChain,
                         const char* filename);
@@ -23,7 +27,8 @@ public:
 
 private:
     static bool SavePPM(const char* filename, 
-                        int width, int height);
+                        int width,
+                        int height);
 };
 
 } // namespace RHI