DnD Coverage Pass

Goal

Add a tiny, fast-lane-only non-React pass for the remaining worthwhile @platejs/dnd seams:

• getNewDirection.ts
• selectBlocksBySelectionOrId.ts

Constraints

• No /react hooks or components.
• Do not reopen onHoverNode, onDropNode, getBlocksWithId, or the already-covered transform helpers.
• Keep this to a pure helper matrix plus one thin coordinator spec.

Slice

1. Add a direct getNewDirection matrix for clear, unchanged, and changed directions.
2. Add selectBlocksBySelectionOrId coverage for:
   • no selection
   • target block already inside the selection
   • target block outside the selection
3. Stop unless a direct test exposes an actual bug.

Notes

• The package already had decent transform coverage from the March 6 cleanup pass.
• The remaining value is just the tiny uncovered helper and routing logic.