[FEAT] Add UV Mapping

[zalo]

This PR adds UV Map Calculation to the models generated by CascadeStudio.

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🔍 Inspect: https://vercel.com/zalo/cascade-studio/9UQf8fkLA8YcFd1XVgEMPDHPLS4A
✅ Preview: https://cascade-studio-git-feat-uv-mapping-zalo.vercel.app

[zalo]

Just added texture atlassing with potpack.

Model View:

UV Space View (before Padding):

Still costs only like 20 milliseconds. A really good deal to enable lightmapping.

[zalo]

Check out the lightmapping demo that this is powering: https://zalo.github.io/three.js/examples/?q=shadowmap#webgl_shadowmap_progressive