Parked (--keep-stash) and conflict-preserved autostash entries were never
mentioned again after the update run that created them — one persisted 9+
days unnoticed (#63717 problem 6). hermes update now lists
hermes-update-autostash-* entries older than 7 days at the start of the
git update path, with review/restore/drop guidance. Deliberately a warning,
not a GC: a stash entry can be the only copy of uncommitted work, so
nothing is ever dropped automatically.