List Block Datasets

Customer-facing Block catalog. Source of truth is the CAMS block_pricing table for prices + neo4j TearSheet for label/description/use-cases. One entry per dataset_id with the cuts that have an active priced row; each cut surfaces the offered access type's annual price and the lag list filtered against the caller's block_client_data_access entries.

Requires a Block role — browsing the catalog is itself a Block feature. The power-ui Block experience is already gated client-side by the same condition (hasAnyBlockAccess); this guard closes the same hole for API-key / SDK callers that bypass the frontend.