Top-down grasping via a fast axis-locked linear descend with a collision-aware cuRobo fallback. A single `grasp_descend_linear` node rises, translates over the target, and descends straight down (Z-locked, orientation held) onto the object; if the straight-line solve is infeasible (far-edge reach, no IK for the fixed wrist) it falls back to the cuRobo planner over the candidate fan. Use when the curobo tool bundle is installed and a perceived object (OBB) must be grasped — the default grasping skill whenever cuRobo is deployed, in clean and cluttered scenes alike.
