Make individual skills available via skills.sh

Installing the whole workflow is great, but some people want only individual pieces/skills. It would be great if skills were distributed via [skills.sh](https://skills.sh/)
And you could do this: `npx skills add garrytan/gstack --skill plan-ceo-review`

This also allows the skills to work on other coding agents outside claude code.

Start by reviewing how this TypeScript repository currently packages and installs its individual skills, then check the skills.sh publishing and installation requirements. Done means the repository supports the demonstrated `npx skills add garrytan/gstack --skill plan-ceo-review` flow and the resulting skill works with coding agents beyond Claude Code.

Written by the indexing model from the issue text.