Clearance layers: VP freeze them for client sets

Don't erase clearance blocks. Freeze them per viewport.

Clearance zones help you check a plan, but the client doesn't need them. Keep them on their own layer (A-FURN-CLR), then in the client viewport use VP Freeze in Layer Properties (or VPLAYER): the clearances disappear there and stay in model space and your design sheet. Set New VP Freeze on that layer so new viewports start clean, and save two layer states, DESIGN and CLIENT, to switch in one click. Off hides a layer; freeze hides it and skips it on regen.