Get Admin Review Report Status

Which ReviewReportConfig an admin-triggered review_report run used.

STABLE is the only variant reachable from every trigger path (customer-facing /reports/review, the review_reporting_stage_wf task, and admin runs that don't opt into an experiment) — see ReviewReportAgent.execute. The other members are experiment levers, selectable only from the admin report-runner, so a regression in one never reaches a customer's review. See ReviewReportConfig.for_variant (backend/analyses/reporting/review.py) for what each one actually changes.