feat: add release-workflow skill

[steve-calvert-glean]

Summary

• Adds .claude/skills/release-workflow/SKILL.md, a user-invocable skill (/release-workflow) that guides through the full release process
• Covers pre-flight checks (version sync, validation, clean working tree), npm run release, post-release verification, and pushing tags
• Lists all 10 plugins covered by the bumper and warns about adding new plugins

Test Plan

• Invoke /release-workflow in Claude Code and verify the checklist appears

[david-hamilton-glean]

Seems okay, although personally this is the kind of thing I'd want to require a HITL rather than have the agent do the release itself.

[steve-calvert-glean]

Seems okay, although personally this is the kind of thing I'd want to require a HITL rather than have the agent do the release itself.

Agree, and it's more about guiding the user to do the release, not letting Agents do it themselves.