docs-ime-render: replace npx wait-on with curl poll (#38787)

Follow-up to #38782. The workflow's server-readiness step used
`npx --yes wait-on`, which fetched the latest wait-on tarball from
npm on every run — non-reproducible, and any compromised release of
wait-on or its transitive deps would run in CI with GITHUB_TOKEN
access.

Adding wait-on as a pinned devDep would fix reproducibility but pull
21 transitive packages (axios, joi, rxjs, @hapi/joi stack) into
package-lock.json just to poll an HTTP endpoint. Replace it with a
one-liner curl retry loop instead — curl ships on every runner, no
npm fetch, no lockfile change, same 10-minute cap.

Reported by @NARSimoes on #38782.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/docs-ime-render.yml

@@ -66,8 +66,11 @@ jobs:
           echo "docusaurus pid $!"
 
       - name: render/wait-for-server
+        # Poll with curl instead of `npx wait-on` — the runner already
+        # ships curl, so this avoids fetching a wait-on tarball (and its
+        # ~20 transitive deps) from npm at run time.
         run: |
-          npx --yes wait-on --timeout 600000 --httpTimeout 5000 http://localhost:3000
+          timeout 600 bash -c 'until curl -sSf --max-time 5 http://localhost:3000 > /dev/null; do sleep 2; done'
 
       - name: render/render-ime
         working-directory: docs/site