fix: menu.ui is now a Menu widget, not a plain JSON list

wwwroot/menu.ui

@@ -1,4 +1,8 @@
-[
+{
+    "widgettype": "Menu",
+    "id": "customer_menu",
+    "options": {
+        "items": [
             {
                 "name": "customers",
                 "label": "客户列表",
@@ -19,4 +23,6 @@
                 "label": "客户交接",
                 "url": "{{entire_url('handover_list.ui')}}"
             }
-]
+        ]
+    }
+}