SI World anatomy assets -- source licenses

1. Spine geometry, baked from:
   BodyParts3D_Vertebral_column.stl
   Source: https://commons.wikimedia.org/wiki/File:BodyParts3D_Vertebral_column.stl
   Credit: BodyParts3D, (c) The Database Center for Life Science,
   licensed under CC Attribution-Share Alike 2.1 Japan.
   License text: https://creativecommons.org/licenses/by-sa/2.1/jp/

2. Brain geometry, baked from:
   3DPX-003765_3DModel_of_Brain_Nevit_Dilmen.stl
   Source: https://commons.wikimedia.org/wiki/File:3DPX-003765_3DModel_of_Brain_Nevit_Dilmen.stl
   Credit: Brain model (c) Nevit Dilmen, CC BY-SA 3.0.
   License text: https://creativecommons.org/licenses/by-sa/3.0/

The files in this directory (spine-hi.bin, spine-lo.bin, brain-hi.bin, brain-lo.bin,
spine-meta.json) are derivative works of the above (welded, decimated, re-encoded as a
compact binary point/mesh format for real-time rendering) and remain licensed
CC BY-SA under the terms above. SocialStack's own code (the bake pipeline, the
renderer/shaders) is not affected by this license and stays under the project's
existing terms.