refactor: use typescript for next.config.ts

Author: hiroppy

next.config.js renamed to next.config.ts

@@ -1,5 +1,6 @@
-/** @type {import('next').NextConfig} */
-const nextConfig = {
+import type { NextConfig } from 'next';
+
+const nextConfig: NextConfig = {
   // logging: {
   //   fetches: {
   //     fullUrl: true,
@@ -22,4 +23,4 @@ const nextConfig = {
   },
 };
 
-module.exports = nextConfig;
+export default nextConfig;