fm.freemix.group.samples

A samples group: a structural grouping of samples uploaded and presented as a unit, independent of any release (FM-824; mirrors fm.freemix.group.stems, FM-549 s38). A sample PACK is this same record with a price — one record type, pricing optional. Points DOWN at its member samples, which carry an optional parentGroup back-ref (the only upward ref); members[] is authoritative for membership and order. RELATIONSHIP TO fm.freemix.release: a release is a separate 'put-out work' wrapper that MAY include this record as one of its members; this record is the structural group itself, not the release. Selling sample packs is NOT implemented — priceCents/currency reserve the shape only.