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/UI/ui.h

@@ -9,7 +9,7 @@
 
 #define UI_MAX_VERTICES 16384
 #define UI_MAX_INDICES  32768
-#define UI_MAX_WIDGETS  256
+#define UI_MAX_WIDGETS 256
 
 typedef struct {
     float x, y;
@@ -31,6 +31,8 @@ typedef struct {
     ID3D11InputLayout* input_layout;
     ID3D11BlendState* blend_state;
     ID3D11RasterizerState* rasterizer;
+    ID3D11ShaderResourceView* font_srv;
+    ID3D11SamplerState* font_sampler;
 
     UIVertex vertices[UI_MAX_VERTICES];
     uint32_t indices[UI_MAX_INDICES];
@@ -47,6 +49,8 @@ typedef struct {
     uint32_t bg_color;
     uint32_t border_color;
     float padding;
+
+    float char_uvs[128][4];
 } UI;
 
 // 创建/销毁
@@ -61,6 +65,7 @@ void ui_render(UI* ui, ID3D11DeviceContext* ctx);
 // 基础绘制
 void ui_draw_rect(UI* ui, float x, float y, float w, float h, uint32_t color);
 void ui_draw_rect_border(UI* ui, float x, float y, float w, float h, uint32_t fill, uint32_t border, float thickness);
+void ui_draw_text(UI* ui, float x, float y, const char* text, uint32_t color);
 
 // 控件
 int ui_button(UI* ui, float x, float y, float w, float h, const char* text);