A shared parent S4 class for composite scatterers that retain a primary body
component together with one or more additional anatomically distinct
sub-components. The CSC-class is intended to provide modular
scaffolding for multi-component biological targets, such as
swimbladder-bearing fish and swimbladder-less fish represented as flesh plus
backbone. It stores the primary body, a general component list, the shared
model output slot, and shape metadata without implying any one specific
resonant or elastic inclusion type.