pull_request_template.md

Why

Closes

What changed

How to review

How to test

# Commands to validate

Impact & rollout

• Backward compatibility:
• Performance:
• Config/env changes:
• Deployment notes:

Checklist

• Tests added/updated
• Changelog entry added (uv run towncrier create ...)
• External docs updated (if user-facing or ops-facing change)
• Internal .md docs updated (internal knowledge and AI code tools knowledge)