Function spawn_linux 

fn spawn_linux(
    bin_name: &str,
    target_exe: &Path,
    cwd: &Path,
    args: &[&str],
    show_console: bool,
) -> Result<Child>

Spawns a process on Linux, querying available terminal emulators when console output is requested.

Decouples standard I/O and creates a separate process group (process_group(0)) so the process outlives the Launcher.