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

server/db.ts

@@ -0,0 +1,15 @@
+import { Pool, neonConfig } from '@neondatabase/serverless';
+import { drizzle } from 'drizzle-orm/neon-serverless';
+import ws from "ws";
+import * as schema from "@shared/schema";
+
+neonConfig.webSocketConstructor = ws;
+
+if (!process.env.DATABASE_URL) {
+  throw new Error(
+    "DATABASE_URL must be set. Did you forget to provision a database?",
+  );
+}
+
+export const pool = new Pool({ connectionString: process.env.DATABASE_URL });
+export const db = drizzle({ client: pool, schema });