nx_face_carve_gate.nx

nx_face_carve_gate.nx -- does CARVING beat MELTING? The additive-smin head melted to a smooth egg (critic couldn't find a face). sdf_face uses the NEW carve op (eye sockets + mouth + nostrils SUBTRACTED). This gate renders BOTH through the same skin shader + scores BOTH with the same critic rulers (nx_critic_axes), and asserts the carved face BEATS the egg -- a MEASURED win for the new capability, not my eyeball. Honest ceiling: still no real eyes/skin-texture, so still expected CLAY -- the claim is carve>melt, not photoreal. license_tier: ORIGINAL expect_exit: 0