v3.0.0-beta.3

Pre-release. Same pins as v3.0.0-beta.2: OCCTSwift 4.0.0-beta.4 exactly, OCCTSwiftIO 2.0.0-beta.1. A consumer only gets this by naming it; the stable line stays at v2.0.0.

New: load(_:id:graph:transform:) takes the caller's BRepGraph (#27)

A host that already holds a graph for a shape passes it in, so a pick's GraphUID resolves in the host's graph and the shape is not graphed twice. graph must have been built from shape as given; with a non-nil transform it is ignored and a fresh graph is minted from the placed shape. load(_:id:transform:) is unchanged.

New: selectionChanges publishes each selection change with its source (#31)

CADViewportService.selectionChanges emits a SelectionChange (previous, current, source). source is .viewportPick, .emptySpaceClick, .programmatic, .agentHighlight(requestID:) or .bodyRemoved(bodyID:). It emits only when the projected selection changed, so a whole-body change does not emit, and removing a body with several selected sub-shapes emits one change. Changes the service cannot attribute (area selection, a pick on an AIS-displayed body) report .programmatic.

Full history in docs/CHANGELOG-OCCTSwiftCADKit.md.