A workflow_dispatch run writes no commit status, so ci-rerun --pr could
never clear the red (pull_request) check it claimed to be re-running for
- it dispatched a fresh run and printed a success message regardless,
even though the check stays red no matter how that run turns out.
--pr now refuses up front, before dispatching, naming the mechanism and
the working alternative (re-run from the web UI). --run and --branch are
unchanged: --run's own PR-pseudo-ref resolution and --branch's direct
dispatch are both untouched.
Fixes the exit-code/honesty defect from #4613; the workflow_dispatch vs.
pull_request event-type question (whether to close+reopen the PR to fire
a real pull_request event) is a separate, parked decision.
92100ac1f8