-- A trusted setting set on the operator's warrant (novox/hq ADR 0277): a layer says who set it.
--
-- Until now a layer carried only when it was set: a layer the operator approved on their phone and one typed
-- at the controller's terminal looked the same, and `settings` could not say "approved by the operator via
-- telegram". Kept with the layer, and with the history copy of it, so the provenance of a replaced layer is
-- read back beside its values.
alter table settings add column set_by text;
alter table settings_history add column set_by text;