Frontend: configure React Router, protected routes, and page structure

[Manak-hash]

Description

Set up the complete routing architecture for the app: all page routes, protected route wrapper, guest-only routes, and the 404 fallback. This is the navigation backbone of the entire frontend.

Tasks

• Define all routes in App.tsx or a dedicated routes.tsx:
  • / → LandingPage (guest only, redirect to dashboard if logged in)
  • /login → LoginPage (guest only)
  • /register → RegisterPage (guest only)
  • /explore → ExploreProjectsPage (public)
  • /projects/:slug → ProjectDetailPage (public)
  • /projects/new → ProjectFormPage (auth required)
  • /projects/:slug/edit → ProjectFormPage (auth required, owner only)
  • /dashboard → DashboardPage (auth required)
  • /profile → ProfilePage (auth required)
  • /profile/:id → PublicProfilePage (public)
  • /applications → MyApplicationsPage (auth required)
  • /bookmarks → BookmarksPage (auth required)
  • /notifications → NotificationsPage (auth required)
  • /admin → AdminDashboardPage (admin only)
  • * → NotFoundPage
• Create ProtectedRoute.tsx — redirects unauthenticated users to /login
• Create AdminRoute.tsx — redirects non-admin users to /dashboard
• Create GuestRoute.tsx — redirects logged-in users away from /login and /register
• Create NotFoundPage.tsx — clean 404 page with back to home button
• Wrap all authenticated pages in AppLayout.tsx (with Navbar)
• Wrap public pages in PublicLayout.tsx (minimal header)

Acceptance Criteria

• All routes resolve to the correct page component
• Unauthenticated users cannot access protected pages
• Non-admins cannot access /admin
• Logged-in users are redirected away from login/register
• 404 page shows for unknown routes