feat: fix push notifications and enhance PWA experience

- Fix InvalidCharacterError in push notifications with proper VAPID key validation
- Add attractive PWA install prompt component with cross-browser support
- Make notification settings always visible regardless of queue status
- Implement PWA install manager with user engagement detection
- Use SvelteKit navigation APIs instead of browser history API
- Add comprehensive error handling and logging
- Include cross-browser compatibility and responsive design
- Add development tooling improvements

Fixes push notification bugs and significantly improves PWA user experience
with modern, accessible interface components and proper error handling.

src/routes/+page.svelte

@@ -5,6 +5,7 @@
 	import type { QueueItem, QueueStatusUpdate } from '$lib/server/queue/types';
 	import QueueItemCard from './components/QueueItemCard.svelte';
 	import NotificationSettings from './components/NotificationSettings.svelte';
+	import { replaceState } from '$app/navigation';
 
 	let items = $state<QueueItem[]>([]);
 	let loading = $state(true);
@@ -204,7 +205,7 @@
 		// Remove highlight parameter from URL without navigation
 		const url = new URL(window.location.href);
 		url.searchParams.delete('highlight');
-		window.history.replaceState({}, '', url.toString());
+		replaceState(url, {});
 	}
 </script>
 
@@ -314,12 +315,10 @@
 		</div>
 	{/if}
 
-	<!-- Notification Settings -->
-	{#if filteredItems.length > 0 || filter !== 'all'}
-		<div class="mt-8">
-			<NotificationSettings />
-		</div>
-	{/if}
+	<!-- Notification Settings - Always visible -->
+	<div class="mt-8">
+		<NotificationSettings />
+	</div>
 
 	<!-- Connection Status -->
 	<div class="fixed bottom-4 right-4">