fix: 附件预览支持默认值

package.json

 {
   "name": "panda-xform",
-  "version": "6.7.8",
-  "description": "6.7.8 搜索位置选择选中",
+  "version": "6.7.9",
+  "description": "6.7.9 附件预览支持默认值",
   "keywords": [
     "panda-xform"
   ],

src/core/FormDesigner/config/settings.js

@@ -1965,6 +1965,10 @@ const fileWidgets = [
         title: '字段说明',
         type: 'string',
       },
+      presetValue: {
+        title: '默认值',
+        type: 'string',
+      },
       hiddenCondition: {
         title: '隐藏条件',
         type: 'string',