v2.14.0 — app down alert (A84)

A84: get alerted when an app worker goes down. Octane, PM2 and Docker sites run a background worker — if it crashes, the site is down even though the server and web server are healthy. The panel now watches each runtime site's worker via Supervisor and raises an alert (with the same Telegram notification + auto-resolve as other alerts) when a worker is stopped, fatal, exited or backing off. Transient states don't alarm. Toggle it on the Alerts page (on by default).\n\nThis completes the post-audit feature roadmap (A78–A84).