rlmesh_box_high
low / high: each entry's type_ is the domain it is stored in (BOOL, UINT or INT for integer bounds, FLOAT otherwise). Whether a bound is None, uniform or per element comes from rlmesh_box_bounds_kind, never from the entry count.
RLMeshStatus rlmesh_box_high(
const RLMeshBox* box,
RLMeshBound* out,
size_t out_cap,
size_t* out_len
)