New nullable Description column (max 4000) on ReleaseEntity, rides the Genre write channel through upload + edit; multiline CMS input. Migration authored, not applied.
Add ReleaseMedium enum (Cut/Session/Mix) and two 1:1 satellite entities
(SessionMetadata, MixMetadata) with EF configs and an additive migration.
ReleaseDto.ReleaseType is now nullable, nulled for non-Cut at the converter.
Existing releases default to Cut via column default; no data migration.