[dependabot:release-train-updater] npm security fix ready but create_pull_request failed (undici override)

## Dependency fix prepared but PR creation failed

A minimal npm security fix is ready but `create_pull_request` failed twice with a
misleading error, so this issue documents the prepared fix for follow-up.

### What was prepared
- Package/ecosystem: npm (root `central-agentic-ops` package)
- Manifest(s): `package.json`, `package-lock.json`
- Change: added `overrides.undici = "6.28.1"` (was resolving to `5.29.0`, transitive
via `@actions/github@^7.0.0` and `@actions/artifact`'s nested `@actions/github`)
- Fixes 5 `npm audit` findings (1 high, 4 moderate), including:
- GHSA-g9mf-h72j-4rw9 (unbounded decompression, high)
- GHSA-2mjp-6q6p-2qxm (request/response smuggling)
- GHSA-vrm6-8vpv-qv8q / GHSA-v9p9-hfj2-hcw8 (WebSocket DoS/unhandled exception)
- GHSA-4992-7rv2-5pvq (CRLF injection via `upgrade` option)
- plus several related lower-severity undici findings
- Avoids the invasive major bump (`@actions/github@9.1.1`) that
`npm audit fix --force` would otherwise require.

### Validation performed
- `npm audit --registry=https://registry.npmjs.org/ --package-lock-only --json`:
0 vulnerabilities after the change (was 5 before).
- Both `package.json` and `package-lock.json` confirmed valid JSON.
- Diff is minimal and scoped: `package.json` +3/-0, `package-lock.json` net
+41/-34, touching only `undici` entries plus removal of the now-unused
transitive `@fastify/busboy` (an `undici@5.x`-only dependency).
- Commit `a55c2420` exists locally on branch
`dependabot-agent/undici-security-fix-20260910075319`, verified via
`git diff origin/main HEAD --stat` (shows exactly the 2 expected files) and
`git log origin/main..HEAD` (shows exactly 1 commit).

### Why this issue instead of a PR
`create_pull_request` was called twice (once with default base, once with
explicit `base: "main"`) and both times returned:

```
{"result":"error","error":"No changes to commit - no commits found",
"details":"No commits were found to create a pull request. Make sure you have
committed your changes using git add and git commit before calling
create_pull_request."}
```

...despite `git log`/`git diff` confirming a real, non-empty commit ahead of
`origin/main`. Per the tool retry policy (max 2 recovery attempts), further
debugging of the underlying patch-generation pipeline was stopped.

### Suggested follow-up
A future workflow run should re-derive this same candidate (the underlying
repository state should be unchanged since no PR landed) and retry
`create_pull_request`, or a maintainer can apply the change manually:

```json
"overrides": {
"undici": "6.28.1"
}
```

then run `npm install --package-lock-only` to regenerate the lockfile.

### Control Plane
- Correlation ID: 34449869936-178
- Central repo: githubnext/gh-aw-cao
- Run URL: https://github.com/githubnext/gh-aw-cao/actions/runs/34449869936

> [!WARNING]
>
> Firewall blocked 4 domains
>
> The following domains were blocked by the firewall during workflow execution:
>
> - `msfeed12.pkgs.visualstudio.com`
> - `msfeed17.pkgs.visualstudio.com`
> - `msfeed2.pkgs.visualstudio.com`
> - `msfeed25.pkgs.visualstudio.com`
>
> To allow these domains, add them to the `network.allowed` list in your workflow frontmatter:
>
> ```yaml
> network:
> allowed:
> - defaults
> - "msfeed12.pkgs.visualstudio.com"
> - "msfeed17.pkgs.visualstudio.com"
> - "msfeed2.pkgs.visualstudio.com"
> - "msfeed25.pkgs.visualstudio.com"
> ```
>
> See [Network Configuration](https://github.github.com/gh-aw/reference/network/) for more information.
>
>

> Generated by [:dependabot: Dependabot / Release Trains](https://github.com/githubnext/gh-aw-cao/actions/runs/34450762242) · copilot · auto · 194.7 AIC · ⌖ 19.6 AIC · ⊞ 18K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-cao+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-cao%2Fdependabot-release-train-updater%22&type=issues)
>

_{Add this agentic workflow to your repo}

To install this agentic workflow, run

```
gh aw add githubnext/gh-aw-cao/.github/workflows/dependabot-release-train-updater.md@main
```

> - [x] expires on Sep 24, 2026, 7:59 AM UTC

Start with package.json and package-lock.json, then review the dependabot-release-train-updater workflow and the failed create_pull_request run. Verify the undici override with npm audit --package-lock-only and confirm the two-file diff; done means the security fix is committed and a pull request can be created successfully.

Written by the indexing model from the issue text.