Group API
Svelte Group props, snippets, callbacks, geometry, and ownership.
Group accepts x, y, width, height, minimum dimensions, resize handle
configuration, metadata, callbacks, groupCallbacks, canContain, and edgePan.
Use title for a text header or headerContent for a custom snippet. The
header is the move surface; the group body remains pointer-transparent so
member nodes receive input.
onMembershipChange and onGeometryChanged are convenience
callbacks composed with their callback-object equivalents. getNodeObject() returns the core group.