feat(viser): overlay sim ground truth - #3835

Greptile Summary

This change adds an optional simulator ground-truth overlay to the Viser manipulation view. It publishes configured MuJoCo body poses, forwards them to the visualization, renders cyan truth markers with visibility controls and a truth-versus-belief distance table, and enables the feature for the xArm room simulation.

No defect was reproduced.

T-Rex validation blocked

• Missing package: The targeted Python harness could not import the project runtime because the git Python module from the GitPython package is unavailable.
• Missing tool: The xArm room simulation asset is stored as a Git-LFS pointer and git-lfs is unavailable, so the configured MuJoCo body names could not be checked against the real room scene.

Confidence Score: 5/5

No verified implementation defect blocks merging.

There are no final severity-bearing findings. Source tracing confirms that matching typed pose streams, visualization forwarding, overlay configuration, marker lifecycle, and cleanup handling are present; the environment prevented execution against the packaged xArm room scene.

Files Needing Attention: If the simulation environment is available, dimos/simulation/engines/mujoco_sim_module.py and dimos/robot/manipulators/xarm/blueprints/simulation.py merit a final runtime check against the Git-LFS-backed xArm room asset.

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