This PR shifts the box lid 1 cm outward（same to metasim/data/quick_start/assets/rlbench/close_box/box_base/mjcf/box_base_unique.mjcf in Roboverse） and removes duplicate visual geoms, eliminating the small self-penetrations that caused MuJoCo to inject huge constraint impulses on the first step. With the fix, the model loads with zero internal contacts, qacc stays near zero, and simulations start smoothly and remain numerically stable.
