fix(map): OverlappingMarkerSpiderfier importiert und Initialisierung korrigiert

- fehlenden Import 'overlapping-marker-spiderfier-leaflet' ergänzt
- Fehler "ReferenceError: OverlappingMarkerSpiderfier is not defined" behoben
- Spiderfy-Funktionalität bei überlappenden Markern jetzt voll funktionsfähig

utils/initializeMap.js

@@ -6,6 +6,7 @@ import "leaflet-contextmenu/dist/leaflet.contextmenu.css";
 import { store } from "../redux/store";
 import * as urls from "../config/urls.js";
 import * as layers from "../config/layers.js";
+import "overlapping-marker-spiderfier-leaflet";
 
 export const initializeMap = (mapRef, setMap, setOms, setMenuItemAdded, addItemsToMapContextMenu, hasRights, setPolylineEventsDisabled) => {
   const mode = process.env.NEXT_PUBLIC_API_PORT_MODE;