v1.45.0

Systematic pass over every docker-mutating operation (#2, thanks @famewolf for the nudge):

• Cleanup can no longer delete an image an update just pulled. docker image prune -a filters on image creation time — an image built upstream days ago but pulled seconds ago was prunable during the update's pull→recreate window. All four cleanup triggers (Telegram /cleanup, Web UI, disk-warning auto-cleanup, post-auto-update cleanup) now take the shared update mutex; manual triggers report the skip, automatic ones retry on their own cadence.
• Stop/start/restart are refused while an update runs. A /stop landing during the post-update health wait read as "unhealthy" and rolled back a perfectly good update. All lifecycle entry points now refuse with an honest message while the mutex is held; the update machinery's own steps are never blocked.
• A self-update queued during cleanup runs right after it.

New i18n keys cleanup_busy / lifecycle_busy.