Function spawn 

pub fn spawn(
    request_id: &str,
    session_id: &str,
    command: &str,
    workdir: Option<PathBuf>,
    env: Option<HashMap<String, String>>,
    timeout_ms: Option<u64>,
    ctx: &AppContext,
    require_background_flag: bool,
    notify_on_completion: bool,
    compressed: bool,
    pty: bool,
    pty_rows: u16,
    pty_cols: u16,
) -> Response

Spawn a bash command in the background. Returns a task_id immediately.