ConstA knob is a plain display value in RoutingModuleConfig, at the path its id names. Not
knobs: layers, beforeLayerConfig and the charging stop icons and title, which take structured
or MapLibre values, and events. A displayUnits knob left unset follows the global config.
Every routing knob with its kind, description, range or options and, where one value holds everywhere, its default: the route-wide knobs first, then each drawn section type's. Static data, readable with no map loaded.