pwa compatible

frontend/src/main.js

@@ -4,3 +4,10 @@ import './styles.css';
 
 const app = createApp(App);
 app.mount('#app');
+
+// Register Service Worker for PWA (in production)
+if ('serviceWorker' in navigator) {
+  window.addEventListener('load', () => {
+    navigator.serviceWorker.register('/sw.js').catch(() => {});
+  });
+}