improve dockerfile

- multi-stage build
- standalone output
- layer caching
- production dependencies

next.config.ts

@@ -15,7 +15,10 @@ const withPWA = require("next-pwa")({
 const nextConfig: NextConfig = withPWA({
 	/* config options here */
 	reactStrictMode: true,
-	// output: "standalone",
+	output: "standalone",
+	images: {
+		formats: ["image/webp", "image/avif"],
+	},
 });
 
 export default nextConfig;