[Tech Debt] Surface the ASF generative-AI disclosure in the PR template #932

Background

The ASF publishes generative tooling guidance, which asks contributors to disclose when generative AI tooling was used to author or co-author a contribution. Our PR template has no field for that today, and AGENTS.md does not mention it either, so the disclosure is not surfaced anywhere in this project.

Two Apache projects already carry it in their PR templates:

• apache/auron uses a minimal form: a yes/no question, a Generated-by: <tool name and version> instruction, and a link to the ASF guidance.
• apache/flink uses a longer form: a checkbox, a commented-out Generated-by trailer, and a pointer to its AGENTS.md for the full policy.

Proposed change

A docs-only change, no behavior impact:

1. Add a "Was this patch authored or co-authored using generative AI tooling?" section to .github/pull_request_template.md, following the shorter apache/auron shape, with a link to the ASF guidance.
2. Add one line to the "Commit & Pull Request Guidelines" section of AGENTS.md recording the same convention, so an agent reading the repo guide knows to fill it in.

I have deliberately left out apache/flink's stronger "low-effort AI-generated PRs will be closed" wording. That is a project policy call rather than a mechanical alignment with the ASF guidance, so it seems better raised separately if maintainers want it.

I'm willing to submit a PR for this.