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3217cb4751
feat: Hub monitoring takeover — event system, dead man's switch, notifications (v0.3.0)
Replace external Healthchecks.io with Hub-native monitoring. New events
table + /api/v1/event endpoint for structured events from controllers.
Staleness checker (60s) detects unresponsive nodes. Backup deadline
checker (daily 05:00) catches missed backups. Notification dispatcher
sends operator (English) + customer (Hungarian) emails via Resend with
per-event cooldowns. Event timeline on customer page, dashboard badges.
Config form deprecates Monitoring UUIDs section.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>