feat: add mock page

src/app/App.tsx

@@ -4,6 +4,7 @@ import { Navigate, Route, Routes } from 'react-router-dom';
 import { AppLayout } from '@/app/layouts/AppLayout';
 import { HomePage } from '@/app/pages/HomePage';
 import { NotFoundPage } from '@/app/pages/NotFoundPage';
+import { RankingPage } from '@/app/pages/RankingPage';
 import { ProtectedRoute } from '@/features/auth/components/ProtectedRoute';
 import { LoginPage } from '@/features/auth/pages/LoginPage';
 import { useAuthStore } from '@/features/auth/store/authStore';
@@ -19,7 +20,10 @@ export default function App() {
       <Route element={<ProtectedRoute />}>
         <Route element={<AppLayout />}>
           <Route index element={<HomePage />} />
-          <Route path="/learn" element={<div>Learn (placeholder)</div>} />
+          <Route path="/vocabulary" element={<div>Vocabulary (placeholder)</div>} />
+          <Route path="/assignment" element={<div>Assignment (placeholder)</div>} />
+          <Route path="/ranking" element={<RankingPage />} />
+          <Route path="/progress" element={<div>Progress (placeholder)</div>} />
         </Route>
       </Route>
       <Route path="/404" element={<NotFoundPage />} />