chore(db): migrate from SQLite to PostgreSQL

- Change Prisma provider from sqlite to postgresql
- Replace better-sqlite3 adapter with @prisma/adapter-pg
- Update prisma.config.ts and lib/prisma.ts for PostgreSQL
- Add DATABASE_URL to .env.local
- Regenerate Prisma client for PostgreSQL
- Recreate migrations for PostgreSQL database

prisma.config.ts

@@ -4,7 +4,7 @@ const config = {
     path: "prisma/migrations",
   },
   datasource: {
-    url: "file:./wikirush.db",
+    url: process.env.DATABASE_URL!,
   },
 };