LightGenBench test shapes

TEXGen-Emission IoU 0.286 / 0.303, MAE 0.0352 / 0.0492 · TRELLIS.2-Emission IoU 0.865 / 0.652, MAE 0.0455 / 0.0468 · Hunyuan3D-Emission IoU 0.531 / 0.447, MAE 0.0285 / 0.0368 · SegviGen-Emission IoU 0.585 / 0.501, MAE 0.2055 / 0.2340 (overall median / mean over 6 rendered objects; a panel scored on fewer shows its n)