actionlint.yml and skill-docs.yml trigger on both push and pull_request
with no concurrency group, so every push to an active branch left the
previous (now-obsolete) runs queued or running — twice per commit on
same-repo PR branches. Add the same cancel-in-progress concurrency
groups the heavier workflows already use, plus a free static tripwire
test that fails CI if a push+pull_request workflow ever ships again
without cancel-in-progress.
Contributed by @jbetala7 (PR #2053).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Garry Tan