feat: 引入 yuxiang-kit 课程组件源码与运行时

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/course-interactions/drag-drop/index.ts

@@ -0,0 +1,13 @@
+export { pointerWithinWithFallback } from "./collision";
+export type {
+	DragDropProviderProps,
+	DraggableProps,
+	DraggableState,
+	DragId,
+	DragOverlayRenderState,
+	DroppableProps,
+	DroppableState,
+} from "./DragDrop.types";
+export { DragDropProvider } from "./DragDropProvider";
+export { Draggable } from "./Draggable";
+export { Droppable } from "./Droppable";