Add Skill

Scaffold a new skill into the infinite-headcount repo and keep the README skills table in sync.

Steps

1. Collect info

Ask the user for:

• Skill name (suggest a kebab-case slug if not provided)
• Invocation type: model-invoked by default, or user-invoked if it only runs when the user explicitly names it
• One-sentence description (what it does and the distinct branches that should trigger it)
• Trigger phrases (optional — keywords that should auto-invoke it)
• MCP tools required (optional)