Add release checklist documentation

[krahd]

Summary

• Added a concise release checklist in docs/RELEASE.md.
• Linked the checklist from the README docs section.
• Updated STATUS.md to keep the release snapshot current.

Added docs/RELEASE.md

• Covers pre-tag checks, PyPI trusted publishing, tagging, post-publish verification, and deferred release-adjacent work.
• Keeps the checklist short and practical rather than duplicating the full status snapshot.

README link

• Added a Release checklist link under the docs/resources section in README.md.

STATUS.md update

• Refreshed the timestamp and kept the remaining external release task explicit.
• Confirmed the repo state still distinguishes verified local checks from PyPI-side configuration.

Checks run

• python -c "import modelito; print(modelito.__version__)" -> 1.4.4
• pytest -q -> 231 passed, 2 skipped

Remaining release task

• Verify PyPI project-side trusted publisher settings before tagging.