with_shared_lock, with_exclusive_lock, try_with_exclusive_lock and the redb
store's with_database returned the unlock's error in place of the action's
result, so a write that had replaced the store could be reported as failed
and read by Odin as not replaced. Closing the lock file releases the lock
whether or not the explicit unlock succeeds, so all four now release through
one helper that returns the action's result. The unlock failure is not
surfaced anywhere: there is no diagnostic channel on these paths.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>