Update joint limits for cell and pedestal configurations

[stevenaya]

Summary

• align configured arm limits and numeric precision with the current OpenArm model
• use the full J1/J2 range for the pedestal configuration while retaining the cell-specific range
• update the gripper limit precision and position-limit tests

Follow-up PRs #27 and #23 have been rebased on top of this change.

Testing

• .venv/bin/pytest -q (40 passed)
• .venv/bin/ruff check .

[kou]

+1

This aligns with https://github.com/enactic/openarm_description/blob/main/assets/robot/openarm_v2.0/config/arm/joint/joint_limits.yaml, right?