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.

.env.example

@@ -22,6 +22,11 @@ DATA_DIR=/data
 # Set to 1 on the one container that should run cron tasks in production
 MAIN_SERVER=
 
+# Web Push: generated into Settings > Environment on first start. Set a
+# fixed pair here only if you want to keep one across installs.
+VAPID_PUBLIC_KEY=
+VAPID_PRIVATE_KEY=
+
 # Optional public envs exposed to the client through __root.server.ts
 PAYSTACK_PUBLIC_KEY=
 R2_PUBLIC_DOMAIN=