The PBS backup snapshot cache only compared BackupCount and LastBackup
timestamp to decide whether to re-fetch. When PBS verify jobs complete,
neither field changes — only the Verification field on individual
snapshots changes — so the cache served stale data indefinitely.
Add a 10-minute TTL per backup group so verification status changes are
picked up periodically. Also add panic recovery to PBS and PVE backup
goroutines, and use runtimeCtx for PBS backup polling to respect
monitor shutdown.
Closes#1174
rcourtman
c8483f8116