perf: bật tối ưu ảnh AVIF/WebP + deviceSizes cho next/image

next.config.ts

@@ -1,7 +1,11 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  /* config options here */
+  images: {
+    formats: ["image/avif", "image/webp"],
+    deviceSizes: [360, 640, 768, 1024, 1280, 1536, 1920],
+    minimumCacheTTL: 2678400,
+  },
 };
 
 export default nextConfig;