Replace the per-username allowlist with a source-org allowlist so no
individual is named in the repo. A non-member PR stays open only if it
adds marketplace.json entries whose source.url is under an allowlisted
prefix and changes nothing else; merge still requires CI + maintainer
approval.
- external-pr-allowed-sources.json: flat allowed_sources prefixes (no usernames)
- scripts/external-pr-scope.js: shared additions-only / allowed-source logic
- close-external-prs.yml + external-pr-scope-guard.yml: both use the shared module
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
