List Transcripts Feature Access

client_ids that currently have the Transcripts product feature enabled — powers the "Transcripts Status" column in the client-pricing table.

Reads the Client Product feature-grant model (feature_client_product_ association), not the legacy ClientFeatureAccess table — per-client grants (ClientProductService.enable_features_by_ids, signup provisioning's set_features) write only to the former, so the latter silently omits every client onboarded through the modern flow.