Function run_gateway 

pub async fn run_gateway(
    host: &str,
    port: u16,
    config: Config,
    external_event_tx: Option<Sender<Value>>,
    reload_controls: Option<GatewayReloadControls>,
    tui_registry: Option<Arc<TuiRegistry>>,
    canvas_store: Option<CanvasStore>,
    sop_engine: Option<Arc<Mutex<SopEngine>>>,
    sop_audit: Option<Arc<SopAuditLogger>>,
) -> Result<()>

Run the HTTP gateway using axum with proper HTTP/1.1 compliance.