configure Next.js for static exports and add GitHub Pages deployment workflow

crypto_clash_frontend/next.config.ts

@@ -1,7 +1,8 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  /* config options here */
+  output: "export",  // <=== enables static exports
+  reactStrictMode: true,
 };
 
 export default nextConfig;