fix(ci): Copilot build uses public registry

[rzhao271]

Verification build: https://dev.azure.com/monacotools/Monaco/_build/results?buildId=444974&view=results

Do not merge until the verification build succeeds.

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@lszomoru

Matched files:

• build/azure-pipelines/copilot/setup-steps.yml

[Copilot]

Pull request overview

Updates the Copilot extension Azure Pipelines setup to explicitly configure the NPM registry (and authentication) during CI, aligning Copilot’s build environment with the registry configuration used by other VS Code product pipelines and ensuring cache keys reflect registry-dependent lockfile content.

Changes:

• Adds a “Setup NPM Registry” step to rewrite package-lock.json registry URLs via build/setup-npm-registry.ts.
• Adds NPM registry + authentication setup (npm config set registry + npmAuthenticate@0) when the Copilot build cache is not restored.
• Bumps the Copilot build cache salt to force a fresh cache.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
extensions/copilot/build/.cachesalt	Cache-busts the Copilot build cache by updating the salt timestamp.
build/azure-pipelines/copilot/setup-steps.yml	Configures NPM registry and authentication in the Copilot pipeline setup steps.

[rzhao271]

New verification build: https://dev.azure.com/monacotools/Monaco/_build/results?buildId=444987&view=results