The backup time is stored as the UTC moment it meant on the day it was set
and was run at that UTC hour every day, so on servers with daylight saving it
ran an hour off the chosen time for part of the year. SetNextBackup now
recovers the clock time with the stored date's offset and runs it on the
server's local days. No migration. Backup manual page and changelog.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
