A notification for one message gets buttons where the browser has room
for them, and a click on its body works as before. The service worker
has no login, so an open tab takes the action first, through the store
actions. With no tab open a new same-origin route, /api/push/action,
does Mark read and Archive with the context cookie. When the cookie is
gone, the token has expired or the login can't be told apart, the
message opens in the app instead. Reply opens the composer through a
`?reply=1` link, with any text typed on the notification.
- `public/sw.js`: buttons, asking open tabs, the route, `sync` handling
- `app/api/push/action`: same-origin, checks the login and the account,
honours the admin's Archive gate, files by the mirrored archive mode
- `lib/pwa-notify`: the page's side, the mirror for the worker, and
`requestOutboxSync`, which the offline queue calls
- Background Sync, thin version: a `sync` event tells open tabs to flush
Two push-preview-route assertions change: they match the whole answer
for a named message, which now also carries `login`, what the action
route checks so a stale notification can't act on whoever holds the
cookie slot now.
