rlmesh_session_step
A Session borrows its model/server until free. Local envs/factories stay exclusively leased until free; close never closes the model.
RLMeshStatus rlmesh_session_step(
RLMeshSession* session,
const RLMeshValue* action,
RLMeshValue** out_observation,
double* out_reward,
bool* out_terminated,
bool* out_truncated,
RLMeshValue** out_info
)