List workbenches for the org (resolver helper)

Resolve a workbench NAME into the workbench_id the workbench nodes need.

Returns {workbenches: [{workbench_id, name, entity_type, description, row_count, created_at}], total, page, limit}.

workbench_id is the value to paste straight into a node config. It is the same id the Workbench page URL shows, so an agent and a human are naming the same thing.

Org is pinned from the authenticated caller and used as the tenant scope; nothing client-supplied selects the tenant.