Make SuiviCPT an installable PWA

Adds what iOS/Android need to treat the site as an installable app
from Safari's "Add to Home Screen": a manifest.json, apple-touch-icon
set generated from the existing logo mark (scripts/generate-icons.mjs,
sharp as a dev dependency), and the apple-mobile-web-app-* meta tags
iOS Safari requires since it ignores manifest.json entirely.

The service worker is deliberately minimal — this app shows live
financial data, so navigations always hit the network first. It only
caches enough to serve offline.html when there's no connection, not a
full offline-first app shell.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -12,6 +12,7 @@
         "concurrently": "^9.0.1",
         "laravel-vite-plugin": "^1.2.0",
         "postcss": "^8.4.31",
+        "sharp": "^0.35.3",
         "tailwindcss": "^3.1.0",
         "vite": "^6.0.11"
     },