Add auth and theme switcher

package.json

@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev --turbopack",
+    "dev": "PORT=3001 NODE_OPTIONS='--max-old-space-size=4096' next dev --turbopack",
     "build": "next build",
     "start": "next start",
     "lint": "next lint"
@@ -22,6 +22,7 @@
     "clsx": "^2.1.1",
     "lucide-react": "^0.525.0",
     "next": "15.3.5",
+    "next-auth": "^5.0.0-beta.29",
     "next-themes": "^0.4.6",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",