Function check 

pub fn check(
    args: &[String],
    root: &Path,
    timeout: Option<Duration>,
) -> (ProbeOutcome, String, String)

Run an okf built-in check: walk the bundle under root/--base and assert every non-reserved .md conforms (parseable frontmatter with a non-empty type); with --strict, also assert no broken bundle cross-links. Returns the probe outcome, a one-line reason, and a violation report. Argument and walk errors are ProbeOutcome::Broken.