The caller workflow had drifted between repos (run-name, stale SHA comment, trigger ordering,
different comment text) though all were functionally the same `uses: agent.yml@main`. Define one
canonical stub: make this repo's own ai-agent.yml the reference and update the README "Use it in a
repo" block to match it verbatim, noting that the on: triggers and the jobs.agent wrapper are the
irreducible minimum for a reusable (workflow_call) workflow.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
