feat: implement Favorites feature with persistent storage and sidebar integration and update lake data.

src/App.tsx

@@ -3,6 +3,7 @@ import { Routes, Route, useParams, useLocation, useNavigate, Navigate } from 're
 import LakeDetail from './components/LakeDetail';
 import LakesOverview from './components/LakesOverview';
 import LakeMap from './components/LakeMap';
+import FavoritesOverview from './components/FavoritesOverview';
 import Sidebar from './components/Sidebar';
 import Topbar from './components/Topbar';
 import SettingsModal from './components/SettingsModal';
@@ -60,6 +61,7 @@ function App() {
         <Topbar language={language} onToggleMobileMenu={() => setIsMobileMenuOpen(!isMobileMenuOpen)} />
         <Routes>
           <Route path="/" element={<LakesOverview language={language} />} />
+          <Route path="/favorites" element={<FavoritesOverview language={language} />} />
           <Route path="/map" element={<LakeMap language={language} />} />
           <Route path="/:slug" element={<LakeDetailWrapper language={language} />} />
         </Routes>