Lists scenarios available for forecast creation, grouped by released market region. Use an exact returned name in simulation_config.scenario when submitting to POST /runs/. Names are case-sensitive and appear once even when several releases are enabled. Submission selects the latest published available matching release at submission time; ties use creation time then ID, and undated releases follow dated releases. Availability is rechecked on submission and is independent of Ko world-view visibility. Regions with no available scenarios return an empty list. Omit the filter to list all released regions.