Function classify_path_step 

pub fn classify_path_step(
    spec: &CommandSpec,
    name: &str,
    current_dir: &Path,
    tail: &[String],
    env: Option<&str>,
) -> PathOutcome

Classify a Path-kind step. Pure: loads the child config, inspects the tail, and returns the matching PathOutcome. The caller owns every side effect (printing, spawning).