rlmesh_remote_env_render
Env construction connects; Model construction only validates. Remote I/O is exclusive, while immutable accessors/cancellation may overlap any call. Accessor pointers remain borrowed until free, including after close.
RLMeshStatus rlmesh_remote_env_render(
RLMeshRemoteEnv* remote_env,
uint64_t env_index,
RLMeshValue** out_frame
)