mix ash_onetime.reap (ash_onetime v0.1.0)

Removes one bounded batch of abandoned processing idempotency recovery points past an abandonment horizon.

mix ash_onetime.reap --repo MyApp.Repo
mix ash_onetime.reap --repo MyApp.Repo --prefix tenant_1 --abandonment-seconds 1209600

A recovery point is reaped only when it is older than --abandonment-seconds, older than the migration's hard 1-day floor, and past its own retention horizon — the delete guard re-enforces all three. --abandonment-seconds must be at least the 1-day floor (86400). Schedule this far less frequently than mix ash_onetime.prune.