fix(coding-agent): guard undici install under Bun

fixes #4657

packages/coding-agent/src/cli.ts

@@ -5,7 +5,7 @@
  *
  * Test with: npx tsx src/cli-new.ts [args...]
  */
-import { EnvHttpProxyAgent, install as installUndiciGlobals, setGlobalDispatcher } from "undici";
+import * as undici from "undici";
 import { APP_NAME } from "./config.js";
 import { main } from "./main.js";
 
@@ -17,11 +17,11 @@ process.emitWarning = (() => {}) as typeof process.emitWarning;
 // (e.g. vLLM buffering a large tool call) exceed that and abort the SSE stream
 // with UND_ERR_BODY_TIMEOUT. Disable both — provider SDKs enforce their own
 // AbortController-based deadlines via retry.provider.timeoutMs.
-setGlobalDispatcher(new EnvHttpProxyAgent({ bodyTimeout: 0, headersTimeout: 0 }));
+undici.setGlobalDispatcher(new undici.EnvHttpProxyAgent({ bodyTimeout: 0, headersTimeout: 0 }));
 
 // Keep fetch and the dispatcher on the same undici implementation. Node 26.0's
 // bundled fetch can otherwise consume compressed responses through npm undici's
 // dispatcher without decompressing them, causing response.json() failures.
-installUndiciGlobals();
+undici.install?.();
 
 main(process.argv.slice(2));