Establish a policy on AI-assisted contributions

[LalatenduMohanty]

With AI coding tools becoming a regular part of many developers' workflows, it might be a good time to discuss how the project would like to handle AI-assisted contributions to Hatch and Hatchling.

There are already PRs in this repo where contributors have used AI tools (e.g., #2206), so having some shared guidelines could help both maintainers and contributors stay on the same page.

Many projects in the Python ecosystem have already adopted policies:

• CPython has an official Generative AI policy in the Developer's Guide
• NumPy, SciPy, SymPy, Pandas, scikit-learn, and Matplotlib all have published AI contribution policies
• A community-maintained list tracks 50+ projects' policies: open-source-ai-contribution-policies

Questions to consider

1. Should AI-assisted contributions be allowed, and under what conditions?
2. Should contributors be required to disclose AI tool usage?
3. Should contributors be expected to understand and maintain the code they submit, regardless of how it was written?
4. Are there licensing/provenance concerns that should be addressed?