rlmesh_dict_key_at
Declaration order; both borrowed while any handle sharing the Dict lives. A child is the same space (and sampler) on every read. An index past the end reads as absent: RLMESH_OK with *out = {NULL, 0} / NULL (a present key's data is never NULL).
RLMeshStatus rlmesh_dict_key_at(
const RLMeshDict* dict,
size_t i,
RLMeshStr* out
)