Salvages #27484 by @fardoche6. Adds a respawn guard that skips worker
spawn for tasks where:
- a recent run already succeeded (recent_success — within guard window)
- the previous run hit a quota/auth error (blocker_auth, also auto-blocks)
- a recent task comment includes a GitHub PR URL (active_pr)
The guard prevents repeat worker storms on the same bug/task. Includes
the contributor's review-findings fixup (regex hardening, observability,
auth coverage).
Resolved a small DispatchResult conflict alongside main's 'stale' field;
kept both. Authorship preserved via rebase merge.
fardoche6
264e85b3dd