A hierarchical container for organizing entities, notebook entries, and other items within
a Project. Folders support nested structures through parent-child relationships (see
parent), enabling users to create logical groupings that mirror laboratory organization
or experimental workflows. Folders belong to a Project (see project) and inherit access
control through collaborations (see Collaboration). Items stored in folders implement
the FolderItem interface. Folders can be starred for quick access (via Starrable) and
archived with lineage tracking that affects contained items (via ArchivableWithLineage).