Function encode_instanced 

pub fn encode_instanced(
    meshes: &[Mesh],
    collated: &Collated,
    entity_id: impl Fn(usize) -> u32,
    color: impl Fn(usize) -> [f32; 4],
) -> Vec<u8> 

encode_refs over geometry Mesh values, with id/colour accessor closures (thin wrapper, no geometry clone).