rlmesh_env_server_env_contract
New binds. start runs callbacks on library threads; serve keeps lane 0 on the caller. shutdown is allowed from a callback. Free shuts down and drains all C callbacks, including any still running past the facade's timeout.
const RLMeshEnvContract* rlmesh_env_server_env_contract(
const RLMeshEnvServer* env_server
)