Function check_token 

pub fn check_token(
    token: &str,
    owner: &str,
    repo: &str,
    needs_workflow: bool,
) -> TokenCheck

Preflight token against owner/repo: does it authenticate, what scopes does it carry (if introspectable), and what access does it have to the repo. Never returns an Err — a failed call surfaces as valid: false or RepoAccess::Error so the caller can report every check even when one of the two calls fails.