Skill Installer

• Use this skill when the user provides a GitHub URL that points to a specific skill folder and asks to bring it into this repo.
• Run the installer script in .github/skills/skill-installer/scripts/install-skill.js with the GitHub URL. The scripts in that folder are chmod +x, so run them directly (no node prefix).
• If the destination folder already exists, ask whether to overwrite before using the --force flag.
• After installation, confirm that the folder exists under .github/skills/ and that SKILL.md is present.