feat(skills): add create-skill skill

[Lefty1995]

What

Adds a create-skill skill that guides agents through scaffolding new Caveman-compatible skills.

Files

• skills/create-skill/SKILL.md — skill definition with frontmatter, rules, examples, auto-clarity, and boundaries
• commands/create-skill.toml — slash command that triggers the scaffold flow

Why

Right now there's no official skill for creating other skills. New contributors or agents trying to add skills to the Caveman ecosystem have no template or guidance — they either guess the format or copy-paste from an existing skill and miss required sections.

create-skill solves this by:

• Teaching the exact SKILL.md structure (frontmatter, activation contract, Rules/Examples/Auto-Clarity/Boundaries)
• Teaching the optional commands/<name>.toml format
• Showing a before/after example of a full scaffold (caveman-changelog)
• Defining clear boundaries (outputs files only, does not run installs)

Trigger

/create-skill caveman-changelog

or: "create a skill", "new skill", "scaffold skill"

How to test

1. Install from fork: npx skills add Lefty1995/caveman
2. In any agent: /create-skill caveman-standup
3. Verify agent outputs skills/caveman-standup/SKILL.md with all required sections and no prose preamble.