Migrate to react-router-dom for SPA routing:
- Add BrowserRouter with nested routes
- Implement AuthGuard component for protected routes
- Add collapsible sidebar navigation
- Support /repos and /config routes
Changes:
- App.tsx: Route definitions with AuthGuard wrapper
- main.tsx: Force dark mode, improved retry logic
- DashboardPage.tsx: New layout with sidebar + Outlet
- vite.config.ts: Expose dev server on 0.0.0.0
Dependencies added:
- react-router-dom
- @radix-ui/react-select, switch, separator, tabs
