[FEATURE] Support for quads

I wanted to ask if this is in the to-do list. There is literally no way out there to compress quad meshes effectively right now. Converting to triangles means you lose all the precious clean quad topology.

No files, tests, or entry points are identified. Start by surveying the Rust format implementation and its mesh encoding path to determine how quad topology is represented and whether it can survive compression and decompression. Done should include an agreed quad representation and validation that quad meshes retain their topology.

Written by the indexing model from the issue text.