Changes made for Pathfinder V5 PC's.

Updated FoldingSolution.cs:388-393 — the validation now only throws when GripperPositions has at least one entry. Machines with no gripper params (like ThalmannZRv1) pass through, and the bogus selectedGripper = 1 from the SequenceManager hack becomes harmless because the downstream _selectedGripper consumers (line 463, CalculateTaperGripperOffset) are already gated to gripper-backgauge paths that no-gripper machines never enter.