Add the callable PR labeler workflow. README badges skipped: no root
README.md exists in this repo (only BACKEND_ARCHITECTURE.md). Dependabot
unchanged.
Part of INFRA-47 (INFRA-56, INFRA-57).
* Add dependency-review caller workflow
Add a pull_request-triggered caller that invokes the org-level
callable-dependency-review workflow to scan dependency changes and
fail on high-severity advisories.
* chore: retrigger checks
* chore: retrigger dep review (post-fix)