SetNextBackup counted "tomorrow" from the day the server started, using the
newest backup file as the last backup, so a restart between midnight and the
backup time (every Thursday reboot), a manual backup, or a backup finishing
after midnight skipped a day. The next backup is now simply the next time the
backup time comes round on the server's clock. A time that happens twice when
the clocks go back runs at the first one only. Tested with a minute-by-minute
simulation over both daylight saving changes (one backup every day; the old
code skipped days) and on the local server. Changelog line; two Deferred
entries (dead inputs, safe headers missing on handler 500s).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>