pm/lock.json and the Npm/AgentBrowser templates record registry.npmjs.org, and
pinned_source handed that URL straight to the downloader, so ~/.npmrc /
npm_config_registry were ignored and closed networks could not provision npm or
agent-browser. pinned_source now routes public-npm URLs through the configured
registry (npm's own precedence: npm_config_registry, then the user npmrc); the
lock's SHA256 still verifies the bytes and progress keeps the lockfile URL.
npm_dist_tags reads from the same registry.
The E2E cell test_npm_registry_mirror_serves_pm_npm_download drops its gate.
Co-authored-by: funky-xamarin <30426178+Wenfengcheng@users.noreply.github.com>