fix: mark MuJoCo-only tooling explicitly

[TATP-233]

Summary

• mark MuJoCo-only boundaries in the affected debug and motion tooling entrypoints
• add a regression test that requires these files to keep an explicit MuJoCo-only marker
• keep the change at the tool/documentation layer without altering runtime behavior

Linked Work

• Issue: Fixes Work: 外围调试工具标注为 MuJoCo-only #231
• Milestone: N/A

Validation

• make check
• uv run pytest -m "not slow"
• Additional task-specific validation listed below

Commands actually run:

make check
make test
uv run pyright scripts/play_interactive.py scripts/motion/csv_to_npz.py scripts/motion/replay_npz.py scripts/motion/bones_seed_csv_to_npz.py scripts/motion/replay_bones_seed_csv.py src/unilab/utils/render_many.py src/unilab/envs/locomotion/g1/symmetry.py tests/scripts/test_mujoco_only_tooling_markers.py
uv run pytest tests/scripts/test_mujoco_only_tooling_markers.py tests/scripts/test_check_docs.py -q

Impact

• Backend impact: none
• Platform impact: both
• Training effect expected: no

Artifacts

• W&B: N/A
• benchmark result: N/A
• video / screenshot: N/A
• ONNX / checkpoint: N/A

Checklist

• Added or updated tests where needed
• Updated docs if behavior or workflow changed
• Linked the driving issue
• Noted any follow-up work explicitly