feat: add admin frontend layout and dashboard

- Add role field to User interface in AuthContext
- Create AdminLayout with responsive sidebar navigation
- Create AdminDashboard with stats cards
- Add admin routes to App.tsx
- Admin panel accessible at /admin
- Shows stats: total users, active subscriptions, pending payments
- Access control: only users with role=admin can access

apps/web/src/App.tsx

@@ -6,6 +6,8 @@ import { Login } from './components/pages/Login'
 import { Register } from './components/pages/Register'
 import { OtpVerification } from './components/pages/OtpVerification'
 import { AuthCallback } from './components/pages/AuthCallback'
+import { AdminLayout } from './components/admin/AdminLayout'
+import { AdminDashboard } from './components/admin/pages/AdminDashboard'
 import { Loader2 } from 'lucide-react'
 
 function ProtectedRoute({ children }: { children: React.ReactNode }) {
@@ -59,6 +61,11 @@ export default function App() {
             <Route path="/auth/otp" element={<OtpVerification />} />
             <Route path="/auth/callback" element={<AuthCallback />} />
 
+            {/* Admin Routes */}
+            <Route path="/admin" element={<ProtectedRoute><AdminLayout /></ProtectedRoute>}>
+              <Route index element={<AdminDashboard />} />
+            </Route>
+
             {/* Protected Routes */}
             <Route path="/*" element={<ProtectedRoute><Dashboard /></ProtectedRoute>} />
           </Routes>