feat(i18n): add internationalization support with i18next

- Add i18next and related dependencies for internationalization
- Implement language switcher component with English and Chinese support
- Create translation files for English and Chinese locales
- Update login and home pages to use translations
- Configure i18n initialization with language detection
- Add dayjs locale synchronization with i18n language changes
- Update tsconfig and eslint to ignore new locales directory
- Remove unused App.css and simplify index.css
- Update npmrc with mirror configuration

src/App.tsx

@@ -2,6 +2,7 @@ import { BrowserRouter } from 'react-router-dom';
 import { CssBaseline, ThemeProvider } from '@mui/material';
 import { theme } from './theme';
 import AppRoutes from './routes';
+import './locales';
 
 function App() {
   return (