Switch to Vector2

Gameboard.ShogiUI.BoardState/Move.cs

@@ -1,10 +1,12 @@
-namespace Gameboard.ShogiUI.BoardState
+using System.Numerics;
+
+namespace Gameboard.ShogiUI.BoardState
 {
   public class Move
   {
     public WhichPiece? PieceFromCaptured { get; set; }
-    public BoardVector From { get; set; }
-    public BoardVector To { get; set; }
+    public Vector2 From { get; set; }
+    public Vector2 To { get; set; }
     public bool IsPromotion { get; set; }
   }
 }