Function scaffold_skill 

pub fn scaffold_skill(
    config: &Config,
    install_root: &Path,
    target: &SkillRef,
    frontmatter: SkillFrontmatter,
    opts: ScaffoldOptions,
) -> Result<PathBuf, ScaffoldError>

Materialize a new skill on disk. Idempotency is not assumed: if the skill dir already exists, an error is returned.