fix(ui): Handle user fetch failure gracefully

- Add catch handler in `fetchUser` to clear user state on request failure
    - Prevent stale user data when `/api/auth/me` request errors

ui/vbase.js

@@ -204,7 +204,9 @@ class VBase {
   }
 
   async fetchUser() {
-    const user = await this.request('GET', '/api/auth/me');
+    const user = await this.request('GET', '/api/auth/me').catch(e => {
+      this.clear()
+    });
     this.user = user;
     return user;
   }