V Core 3.1 toolhead front using a clip

This augment the m3 screw to m6 size for belt clip, to avoid breaking belts.

NOT tested yet.

2025-01-10: reduced the x stop mount, old version needs some cut

Instead of a m4 screw to clamp the belt, this uses a simple belt clip (like ) mainly to avoid cutting belt tightly. We could use the original front, but I'm afraid of the m3 screw bolt may cut the belt soon or later.