Continuous soak of the merge-recovery suite against a live shard.
Friday 19:30 → Monday 07:30 Pacific. Fixed span every week, so the
numbers are the week-over-week baseline and gate releases.
Mon–Thu 19:30 Pacific, up to 22h. Skipped when nothing new landed,
and stops early once dev advances — so spans vary and these
numbers are signal, not a release gate.