[dependabot:release-train-updater] npm install blocked by ms-feed proxy mirror 403s, prevents copilot-sdk 1.0.11→1.0.13 patch update

### Summary
Repeated dependency-release-train runs cannot safely upgrade `@github/copilot-sdk` from `1.0.11` to `1.0.13` (or perform any real npm install that changes the lockfile) in this sandbox because `npm install` routes many transitive tarball fetches through `ms-feed-*.pkgs.visualstudio.com` proxy mirrors instead of `registry.npmjs.org`, and those mirror requests return `403 Forbidden`.

### Evidence
- `npm install @github/copilot-sdk@1.0.13 --save-exact` completes (exit 0) but does **not** update `package.json`/`package-lock.json` — `@github/copilot-sdk` remains pinned at `1.0.11` and `npm ls` reports it as `invalid`.
- npm debug log (`~/.npm/_logs/*-debug-0.log`) shows dozens of `403` responses for packages such as `remark-directive`, `rehype-raw`, `parse5`, `micromark-*`, `mdast-util-*`, `yaml`, fetched via `(msfeed2.pkgs.visualstudio.com/redacted) and `(msfeed12.pkgs.visualstudio.com/redacted) instead of the npm public registry directly.
- This same blocker has now been observed across at least 4 consecutive scheduled runs of the dependabot release-train-updater worker (correlation IDs from prior runs on 2026-09-06), with no change in behavior.

### Impact
- No dependency PRs can currently be produced by the automated release-train worker for the root `package.json`/`package-lock.json` in this environment, since any real version bump touches transitive packages that get routed through the blocked proxy mirrors.
- The intended low-risk patch update (`@github/copilot-sdk` 1.0.11 → 1.0.13, reachable in `dashboard/local-server.mjs`) remains blocked purely by sandbox network routing, not by any code or compatibility issue.

### Suggested remediation
- Configure the CI/sandbox network egress or npm registry config (e.g. `.npmrc` proxy allowlist) so that `registry.npmjs.org` package tarball requests are not silently rewritten to `ms-feed-*.pkgs.visualstudio.com` mirrors, or ensure those mirrors are allow-listed and return valid (non-403) responses.
- Alternatively, if the mirror is intentional, ensure it mirrors the full npm registry (not just a subset) so unrelated transitive packages resolve successfully.

### Control Plane
- Correlation ID: 34054335462-94
- Central repo: githubnext/gh-aw-cao
- Run URL: https://github.com/githubnext/gh-aw-cao/actions/runs/34054335462

> [!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/34054559593) · copilot · auto · 48.8 AIC · ⌖ 13.6 AIC · ⊞ 20.5K · [◷](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 20, 2026, 7:29 PM UTC

Start with the root package.json and package-lock.json, then reproduce the npm install from the dependabot release-train updater and inspect the npm debug log for the blocked ms-feed requests. Check the workflow network configuration and the .npmrc proxy settings mentioned in the issue; done means the copilot-sdk update can change the lockfile and npm ls no longer reports it as invalid.

Written by the indexing model from the issue text.