When adding a print to the queue for multiple printers, users can now
enable "Stagger printer starts" to avoid power spikes from simultaneous
bed heating. Configurable group size and interval — first group starts
immediately (ASAP) or at scheduled time, subsequent groups get offset
scheduled_time values. No backend queue/scheduler changes — leverages
existing scheduled_time field.
Also adds a dedicated Queue tab in Settings (stagger defaults + auto-
drying moved from Filament tab), i18n keys for all 7 locales, frontend
and backend tests.
maziggy
68dce24cc9