Function install_panic_hook 

pub fn install_panic_hook(raw: &[OsString])

Keeps the JSON contract when skif itself panics: in --format json mode stdout still receives exactly one error document (kind internal) and the process exits 2, instead of aborting with a bare message on stderr.

For the skif binary only; an embedding host owns its own panic handling. Without --format json the default hook is left alone.