New BackupSettings.EveryExit (keyBackupEveryExit) with a Settings → Backup
checkbox. When on, the three shutdown-backup gates (plannedShutdownSteps,
runBackupForShutdown, maybeShutdownBackup) bypass the HasBackupToday /
HasADIFBackupToday "already done today" check and always run, so a second
session's QSOs are captured instead of skipped until the next day. The dated
backup file for today is refreshed (overwritten) each exit; prior days are still
kept by rotation.