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/VisualScript/block_interaction.c

@@ -116,11 +116,25 @@ void interaction_key_down(BlockInteraction* inter, BlockWorkspace* ws, int key)
     }
     
     // 复制/粘贴 (Ctrl+C / Ctrl+V)
+    static Block* clipboard = NULL;
     if (key == 'C' && (GetAsyncKeyState(VK_CONTROL) & 0x8000)) {
-        // TODO: 复制到剪贴板
+        if (inter->selected_block) {
+            if (clipboard) block_destroy(clipboard);
+            clipboard = block_copy(inter->selected_block);
+        }
     }
     if (key == 'V' && (GetAsyncKeyState(VK_CONTROL) & 0x8000)) {
-        // TODO: 从剪贴板粘贴
+        if (clipboard) {
+            Block* copy = block_copy(clipboard);
+            if (copy) {
+                copy->x += 20.0f;
+                copy->y += 20.0f;
+                copy->id = ws->next_block_id++;
+                workspace_add_block(ws, copy);
+                inter->selected_block = copy;
+                ws->selected_block = copy;
+            }
+        }
     }
 }