Function run_migrate_command 

pub fn run_migrate_command(
    data_dir: &Path,
    dry_run: bool,
    list: bool,
    verify: bool,
) -> i32

Called from main.rs when the migrate subcommand is active. Returns the exit code (0 = success, 1 = failure, 3 = --verify found a mismatch — see VERIFY_FAILED_EXIT_CODE).