refactor: configure vite and next.js for correct module loading

frontend/index.html

@@ -8,6 +8,6 @@
   </head>
   <body>
     <div id="root"></div>
-    <script type="module" src="/src/main.tsx"></script>
+    <script type="module" src="/src/main.tsx" defer></script>
   </body>
 </html>