If the agent bead doesn't exist when gt done tries to clear the hook,
return early instead of failing. This happens for polecats created
before identity beads existed.
gt done must be resilient and forgiving - the important thing is work
gets submitted to merge queue, not that cleanup succeeds.
Fixes: hq-i26n2
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
cdea53e221