feat: 完善课程模板通用能力

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/course/interactions/drag-drop/collision.ts

@@ -0,0 +1,15 @@
+import {
+	type CollisionDetection,
+	closestCenter,
+	pointerWithin,
+} from "@dnd-kit/core";
+
+export const pointerWithinWithFallback: CollisionDetection = (args) => {
+	const pointerCollisions = pointerWithin(args);
+
+	if (args.pointerCoordinates) {
+		return pointerCollisions;
+	}
+
+	return pointerCollisions.length > 0 ? pointerCollisions : closestCenter(args);
+};