[codex] Self-host public model assets

[abcamiletto]

Summary

• Point redistributable model auto-downloads at abcamiletto/body-models on Hugging Face.
• Add BrainCo and MHR public hosted assets, including MHR LOD 0-6 support through preprocessed FBX-derived assets.
• Normalize hosted folders to LICENSE.md plus assets.zip, including GarmentMeasurements.
• Simplify shared ZIP download/extract handling now that hosted assets use normalized archives.

Validation

• uv run ruff check
• GarmentMeasurements hosted ZIP smoke test
• BrainCo left/right hosted ZIP smoke test
• MHR LOD 6 hosted ZIP smoke test
• uv run pytest ran with 77 passed, 2 skipped, 1 failure in existing SOMA arbitrary-leading-dim sparse matmul path: tests/test_backend_consistency.py::test_forward_accepts_arbitrary_leading_dimensions[soma-SOMA-SOMA-SOMA-kwargs12]. This path was not changed by the asset-hosting work.

Hugging Face assets

• Public model repo: https://huggingface.co/abcamiletto/body-models
• Added/updated folders for ANNY, BrainCo, G1, GarmentMeasurements, MHR, MyoFullBody, and SOMA.