Function build_lod_chain 

pub fn build_lod_chain(
    source: &Mesh,
    options: LodChainOptions,
    out_buffer: &mut [u8],
) -> Result<LodChainReport, LodChainError>

Build a LOD chain from a source mesh and serialize all levels as .10d QuantizedMesh sections into out_buffer.

Returns a report with per-level stats and the total bytes written.

This is a cold builder (uses Vec scratch for decimation and encoding). The output is caller-owned and deterministic.