refactor(channels): dedupe transport and gateway test scaffolds

src/gateway/server.chat.gateway-server-chat.e2e.test.ts

@@ -1,7 +1,7 @@
 import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
-import { afterAll, beforeAll, describe, expect, test, vi } from "vitest";
+import { describe, expect, test, vi } from "vitest";
 import { WebSocket } from "ws";
 import { emitAgentEvent, registerAgentRunContext } from "../infra/agent-events.js";
 import { GATEWAY_CLIENT_MODES, GATEWAY_CLIENT_NAMES } from "../utils/message-channel.js";
@@ -11,29 +11,20 @@ import {
   installGatewayTestHooks,
   onceMessage,
   rpcReq,
-  startServerWithClient,
   testState,
   writeSessionStore,
 } from "./test-helpers.js";
 import { agentCommand } from "./test-helpers.mocks.js";
+import { installConnectedControlUiServerSuite } from "./test-with-server.js";
 
 installGatewayTestHooks({ scope: "suite" });
 
-let server: Awaited<ReturnType<typeof startServerWithClient>>["server"];
 let ws: WebSocket;
 let port: number;
 
-beforeAll(async () => {
-  const started = await startServerWithClient(undefined, { controlUiEnabled: true });
-  server = started.server;
+installConnectedControlUiServerSuite((started) => {
   ws = started.ws;
   port = started.port;
-  await connectOk(ws);
-});
-
-afterAll(async () => {
-  ws.close();
-  await server.close();
 });
 
 async function waitFor(condition: () => boolean, timeoutMs = 1500) {