🎨 fix: Import Semi UI CSS explicitly to resolve missing component styles

- Add explicit import of '@douyinfe/semi-ui/dist/css/semi.css' in index.js
- Ensures Semi Design components render with proper styling
- Resolves issue where Semi components appeared unstyled after dependency updates

This change addresses the style loading issue that occurred after adding antd
dependency and updating the build configuration. The explicit import ensures
consistent style loading regardless of plugin behavior changes.

web/src/index.js

 import React from 'react';
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import ReactDOM from 'react-dom/client';
 import { BrowserRouter } from 'react-router-dom';
 import { BrowserRouter } from 'react-router-dom';
+import '@douyinfe/semi-ui/dist/css/semi.css';
 import { UserProvider } from './context/User';
 import { UserProvider } from './context/User';
 import 'react-toastify/dist/ReactToastify.css';
 import 'react-toastify/dist/ReactToastify.css';
 import { StatusProvider } from './context/Status';
 import { StatusProvider } from './context/Status';