RoboLab v0.3.1

Added

• Kinova Gen3 (Robotiq 2F-85) fixed-base support: robot config, joint-position
  environment registrations, and an example runner
  (examples/run_kinova_jointpos.py).
  (#23)
• Floor-standing robot support: a robot config can declare the
  root_z_above_ground label (the reach of its lowest colliders below the
  root), and the environment factory places the root on each task scene's
  authored ground plane plus that offset (docs/robots.md).
• Per-scene ground-height lock (tests/test_scene_ground.py): the task table
  is a dynamic rigid body resting on the ground plane, so the authored ground
  height sets the tabletop height and is now locked per scene.

Changed

• Every robot config must now declare the ee_recorder_bodies label mapping
  HDF5 channel names to the articulation bodies recorded for end-effector
  pose ({} opts out). Breaking for custom robot configs: environment
  generation fails with a ValueError naming the config until the label is
  added — see docs/robots.md#end-effector-pose-recording.
• Remaining task-scene ground planes aligned to the canonical -0.697 height;
  legacy scenes keep their original -0.65 ground to preserve replay
  compatibility with existing recordings.