Enable users to manage video playlists and mark favorite content

Adds new user, playlist, and favorites management API endpoints and React components.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 50814a1e-92e4-4968-856f-7bc7eedf5e8f
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/50814a1e-92e4-4968-856f-7bc7eedf5e8f/hISDNbZ

client/src/App.tsx

@@ -5,6 +5,8 @@ import { Toaster } from "@/components/ui/toaster";
 import { TooltipProvider } from "@/components/ui/tooltip";
 import Home from "@/pages/home";
 import VideoPage from "@/pages/video";
+import { PlaylistsPage } from "@/pages/playlists";
+import { FavoritesPage } from "@/pages/favorites";
 import NotFound from "@/pages/not-found";
 
 function Router() {
@@ -12,6 +14,8 @@ function Router() {
     <Switch>
       <Route path="/" component={Home} />
       <Route path="/video/:id" component={VideoPage} />
+      <Route path="/playlists" component={PlaylistsPage} />
+      <Route path="/favorites" component={FavoritesPage} />
       <Route component={NotFound} />
     </Switch>
   );