Function failure_class_for_subprocess_error 

pub fn failure_class_for_subprocess_error(
    err: &SubprocessInvokerError,
) -> FailureClass

Map a SubprocessInvokerError onto the shared FailureClass vocabulary.

Pure function: same variant always maps to the same class so a receipt ledger replays consistently. Stays aligned with the in-process TransportError mapping in super::failure_mapping (private).