Function run_train_differentials 

pub fn run_train_differentials(
    repo: &Path,
    train: &Train,
    runner: &Path,
    command_file: &Path,
    state_dir: &Path,
) -> Vec<(u64, Result<DifferentialOutcome, String>)>

Runs the advisory detector for every merge commit in a train, preserving train order and returning operational errors per entry instead of turning them into a landing decision.