feat(nginx): enable websocket support in reverse proxy

Enabled `proxyWebsockets` for the nginx reverse proxy configuration to support websocket connections. This ensures compatibility with services requiring websocket communication.

systems/x86_64-linux/sgx/nginx.nix

@@ -27,6 +27,7 @@
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://127.0.0.1:${toString config.services.open-webui.port}";
+          proxyWebsockets = true;
         };
       };
     };