Make the app an installable PWA with phone layout and Web Push

Add a generated manifest, icon set, offline page and service worker that never caches authenticated HTML, plus install and update UI. Turn the rail into a drawer below md with container-query internals, dvh and safe-area handling, and reconnect the socket after visibility/network changes. Add Web Push subscriptions, presence-aware delivery, notification settings and tests.

package.json

@@ -29,6 +29,7 @@
         "@types/react-dom": "^19.2.4",
         "@types/sanitize-html": "^2.16.2",
         "@types/turndown": "^5.0.6",
+        "@types/web-push": "^3.6.4",
         "tailwindcss": "^4.3.3"
     },
     "peerDependencies": {
@@ -61,6 +62,7 @@
         "tailwind-merge": "^3.6.0",
         "turndown": "^7.2.4",
         "unpdf": "^1.8.0",
+        "web-push": "^3.6.7",
         "xlsx": "^0.18.5",
         "zod": "4.1.12"
     }