Release v0.2.0

[0.2.0] - 2026-03-16

• Added vision-based PPO training configs for CartpoleBalance and
  PandaPickCubeCartesian with tuned hyperparameters.
• Update vision notebooks to use MuJoCo Warp.
• Default MuJoCo implementation for all envs is now MuJoCo Warp.
• Renamed deprecated nconmax / nccdmax config fields to naconmax /
  naccdmax across all environments, matching the updated MJX API.