flipSide

Creates a new Position identical to the current one, but with the active side toggled.

This method is used to pass the turn to the opponent without making a move on the board. It is primarily utilized in null-move pruning or specific evaluation techniques.

Constraint: * The turn cannot be flipped if the current side is in check or checkmate. Flipping the turn in such a state would result in an illegal position (a state where the king could be captured), which is not permitted by this engine's logic.