fix: register SvelteKit service-worker.js instead of static sw.js

frontend/src/app.html

@@ -17,7 +17,7 @@
 		<script>
 			if ('serviceWorker' in navigator) {
 				window.addEventListener('load', () => {
-					navigator.serviceWorker.register('/sw.js', { scope: '/' })
+					navigator.serviceWorker.register('/service-worker.js', { scope: '/' })
 						.then(reg => console.log('[SW] Registered:', reg.scope))
 						.catch(err => console.warn('[SW] Registration failed:', err));
 				});