fix: 优化拖拽排序响应式更新，确保流水线分组预览同步更新

frontend/src/views/CreateTask.vue

@@ -971,14 +971,12 @@ const handleDrop = (e: DragEvent, targetIndex: number) => {
     return
   }
   
-  // 交换位置
+  // 交换位置 - 使用 splice 原地修改数组以确保响应式更新
   const sourceIndex = dragIndex.value
-  const items = [...formData.taskTypes]
-  const [removed] = items.splice(sourceIndex, 1)
-  items.splice(targetIndex, 0, removed)
-  formData.taskTypes = items
+  const [removed] = formData.taskTypes.splice(sourceIndex, 1)
+  formData.taskTypes.splice(targetIndex, 0, removed)
   
-  // 重新计算积分
+  // 重新计算积分（pipelineGroups 是 computed，会自动更新）
   calculateScore()
   
   handleDragEnd()