Consider using Konva.Group for multipart objects

See if handling e.g. the fungus in LZ would be easier if the parts were defined as a Group object.

(The jersey & jersey number in LZ could also be handled as a Group?)

Review how multipart objects such as the fungus and the jersey with its number are currently represented in LZ, then assess whether grouping their parts would simplify handling. Identify the affected object-handling entry points and define the expected behavior before implementation; done means both examples behave correctly as grouped multipart objects.

Written by the indexing model from the issue text.