- Update main PR template to emphasize CHANGELOG entries for every behavior change
- Add clear example of how to format CHANGELOG entries
- Create separate release_pr_template.md with comprehensive release checklist
- Move release checklist to bottom of main template with reference to separate template
The templates now institutionalize the plan §7 CHANGELOG pattern:
- Regular PRs: add entry under [Unreleased] with clear format guidance
- Release PRs: use dedicated template with full checklist matching plan §7
Closes: miroir-uyx.2
