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.

package.json

@@ -5,6 +5,7 @@
     "type": "module",
     "scripts": {
         "dev": "vite dev",
+        "dev:host": "vite dev --host",
         "build": "vite build",
         "preview": "vite preview",
         "prepare": "svelte-kit sync || echo ''",