Drain the pending FV outbox, expire runs past their deadline, and re-drive READY runs whose GitHub write-back failed transiently.

The sweeper (pure DB, deadline expiry) runs on every tick regardless of whether the pipeline is currently configured, so a run stranded by a mid-flight disable is still terminalised. The pending-outbox drain runs only when FV is live. The write-back re-drive (see _redrive_fv_writeback_failures) runs whenever the GitHub App is configured and never fails the tick.