A dense, 4-level hierarchy (~250 nodes). Dot nodes with labels that fan out along each spoke, curved radial links
(direction: 'radial'). Toggle the layout: Dendrogram pins every leaf to the outer
ring (layoutType: 'cluster'); Tidy tree places leaves by depth (layoutType: 'tree') and declutters the crowded inner rings with externalLabel.collisionStrategy: 'hide'.