OpenStreetMap and Apple MapKit providers

The provider-neutral map control gains two new renderers: OpenStreetMap (drawn with a bundled Leaflet — no API key and no external scripts, only the map tiles come from openstreetmap.org) and Apple MapKit (needs a MapKit JS token). A deployment picks its map provider by listing exactly one provider module in its configuration — Google Maps remains the default — and every page showing a map stays identical across providers: same markers, circles, and click behavior.