fix(robomp): route issues.reopened to admission-gated re-triage

The finalized-issue boilerplate promises "reopen and I'll triage again from
scratch," but github_events.route() dropped issues.reopened to the ignored
skip branch (only opened/closed handled), while pull_request.reopened was
already routed. A user following the instruction got silence.

Route issues.reopened like issues.opened (submitter-attributable triage_issue,
same per-user rate budget) and dispatch it in queue._dispatch(). triage_issue
now tears down a stale finalized workspace (merged/closed/abandoned) before
re-provisioning, mirroring the maintainer directive-reopen teardown so the
re-triage branches afresh from default instead of a merged/deleted branch.

Fixes #5891

python/robomp/src/queue.py

@@ -382,7 +382,7 @@ class WorkerPool:
                 "recovered": row.attempts >= 2,
             },
         )
-        if event == "issues" and action == "opened":
+        if event == "issues" and action in ("opened", "reopened"):
             await tasks.triage_issue(
                 settings=self.settings,
                 db=self.db,