Skill: update-changelog

Update CHANGES.md with entries for all issues and PRs in a given GitHub milestone. Each entry references the user-facing issue (not the PR) as the primary link, with the fix PR inline on the same line.

When to Use

• Before a new release, to populate the changelog with all fixed issues
• When new issues are added to an existing milestone and the changelog needs to be refreshed
• To ensure every entry follows the correct format for the changelog

Prerequisites

• gh CLI authenticated (gh auth status)
• Python 3.8+
• scripts/gh.py for GitHub queries, scripts/changelog.py for changelog checks (run python3 scripts/changelog.py <command> --help for usage)