支持缩略图加载，故事项新建调整

src/pages/story/detail.tsx

@@ -91,22 +91,7 @@ const Index = () => {
       </div>
       <FloatButton onClick={() => {
         setCurrentOption('add');
-        setCurrentItem({
-          coverInstanceId: "",
-          createTime: "",
-          description: "",
-          id: 0,
-          images: [],
-          instanceId: "",
-          isRoot: 0,
-          location: "",
-          masterItemId: "",
-          storyInstanceId: "",
-          storyItemTime: "",
-          subItems: [],
-          title: "",
-          updateTime: ""
-        });
+        setCurrentItem();
         setOpenAddItemModal(true);
       }} />
       <AddTimeLineItemModal