Function dispatch_step_instance 

pub async fn dispatch_step_instance(
    run_id: RunId,
    step_instance_id: StepInstanceId,
    step_name: &str,
    step_type: &str,
    resolved_spec: &Value,
    resolved_params: &Value,
    nats_client: Client,
    pool: PgPool,
    tls_reloader: Arc<TlsReloader>,
) -> Result<()>

Dispatches a step instance, handling intrinsic types or forwarding to runners via NATS.