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/dashboard.webmanifest

@@ -14,19 +14,25 @@
   ],
   "icons": [
     {
-      "src": "/icons/dashboard-icon-192.png",
+      "src": "/icons/v2/dashboard-icon-192.png",
       "sizes": "192x192",
       "type": "image/png",
       "purpose": "any"
     },
     {
-      "src": "/icons/dashboard-icon-512.png",
+      "src": "/icons/v2/dashboard-apple-touch-icon-180.png",
+      "sizes": "180x180",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icons/v2/dashboard-icon-512.png",
       "sizes": "512x512",
       "type": "image/png",
       "purpose": "any"
     },
     {
-      "src": "/icons/dashboard-icon-maskable-512.png",
+      "src": "/icons/v2/dashboard-icon-maskable-512.png",
       "sizes": "512x512",
       "type": "image/png",
       "purpose": "maskable"