Serve PWA icons from fresh /icons/v2/ URLs with every iOS size

iOS showed a letter tile ('N') when adding to the Home Screen. The live files were fine, but a
reverse proxy in front of the app serves static files with a long cache lifetime (live icon.svg
and sw.js were stale) and iOS remembers a failed icon per URL.

- New versioned URLs no proxy/phone has cached; old paths kept for existing installs
- apple-touch-icon declared at 180/167/152/120 (opaque 8-bit RGB PNGs) for app and dashboard
- 180px icon also listed in both manifests; notification icons and root fallbacks use v2
- Service worker cache bumped

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/public/app.js

@@ -2083,10 +2083,10 @@ function renderAlerts(data) {
     if (typeof Notification !== 'undefined' && Notification.permission === 'granted') {
       if ('serviceWorker' in navigator && navigator.serviceWorker.controller) {
         navigator.serviceWorker.ready.then(reg =>
-          reg.showNotification(title, { body, icon: '/icons/icon-192.png', badge: '/icons/icon-192.png', tag: id, data: { url: '/?tab=alerts' } })
-        ).catch(() => new Notification(title, { body, icon: '/icons/icon-192.png' }));
+          reg.showNotification(title, { body, icon: '/icons/v2/icon-192.png', badge: '/icons/v2/icon-192.png', tag: id, data: { url: '/?tab=alerts' } })
+        ).catch(() => new Notification(title, { body, icon: '/icons/v2/icon-192.png' }));
       } else {
-        new Notification(title, { body, icon: '/icons/icon-192.png', badge: '/icons/icon-192.png' });
+        new Notification(title, { body, icon: '/icons/v2/icon-192.png', badge: '/icons/v2/icon-192.png' });
       }
     }
     if (state.ntfyTopic) {