ConstA knob is a plain display value in POIsModuleConfig, at the path its id names: whether
POIs show, which categories, and how they look — size, zoom, label colours, micro markers. Those
restyle the style's own POI layers, and read its own value while unset. Not knobs:
icon.categoryIcons, which takes images, and events.
Every POIs knob with its kind, description, options and, where one value holds everywhere, its default. Static data, readable with no map loaded.