This PR adds an automated AgentScan workflow to help detect and handle
pull requests that appear to be created or authored primarily by
automated agents.
- If a PR is classified as `automation` or community-flagged, the
workflow:
- Adds the `possible bot` label,
- Posts a policy comment linking to the repository AI Contribution
Policy (`CONTRIBUTING.md#ai-contribution-policy`) and listing required
disclosures and checks,
- Optionally closes the PR if classification indicates an
automated/unwelcome submission.