After a Scissors cut (`path.split`) the whole path stayed selected: both
pieces of an open path, or the opened path of a closed one. A Direct
Selection drag from the cut then moved every anchor, so an ellipse cut
at an anchor could not be pulled open by dragging its end.
- `path.split` selects the first anchor of the piece after the cut and
nothing else, as `path.cutAtAnchors` does: anchor 0 of an opened
closed subpath, of the new path when an open path becomes two, or of
the subpath added to a path of several subpaths.
- A Direct Selection press on anchors of a selected path that lie on top
of each other takes the selected one. It took the first in path order,
which in a path of several subpaths was the unselected end.
Docs: docs/mcp.md, docs/target-app-parity.md, the `path.split` params
text.