feat: major engine overhaul - scene demo with lighting, sphere, ground

- Scene Demo: cube + sphere + ground plane with proper lighting
- Audio: XAudio2 dynamic loading + WAV playback
- Physics: expanded collision system
- Renderer: improved pipeline with materials
- UI: extended widget system
- VisualScript: enhanced serializer + block interactions
- ASM: optimized math/memory/profiling routines
- Window: mouse input + scroll support

Engine/Rendering/graphics_device.h

@@ -3,7 +3,8 @@
 #include <dxgi.h>
 #include <stdint.h>
 
-typedef struct {
+typedef struct GraphicsDevice GraphicsDevice;
+struct GraphicsDevice {
     ID3D11Device* device;
     ID3D11DeviceContext* context;
     IDXGISwapChain* swap_chain;
@@ -13,7 +14,7 @@ typedef struct {
     uint32_t width;
     uint32_t height;
     int vsync;
-} GraphicsDevice;
+};
 
 GraphicsDevice* graphics_device_create(void);
 void graphics_device_destroy(GraphicsDevice* d);
@@ -21,3 +22,4 @@ int graphics_device_init(GraphicsDevice* d, void* hwnd, uint32_t w, uint32_t h,
 void graphics_device_resize(GraphicsDevice* d, uint32_t w, uint32_t h);
 void graphics_device_clear(GraphicsDevice* d, float r, float g, float b, float a);
 void graphics_device_present(GraphicsDevice* d);
+int graphics_device_save_screenshot(GraphicsDevice* d, const char* path);