Fully progressive: without VAPID keys in the environment the API says
404, the bell never renders, and the service worker addition (a push
handler via workbox importScripts — no SW strategy change) is inert.
With keys: a bell on each team page requests permission, subscribes
(one team per device) and the server diffs fixture states on every
broadcast to push Kickoff / Goal / Full time to that team's followers.
Dead endpoints (404/410) self-clean. Round-trip verified locally with
dev VAPID keys; disabled mode verified too.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
