Warehouse zone occupancy heatmap

Visualize live per-zone occupancy on the warehouse detail page.

apps/edr-freight-web/backoffice/src/hooks/useWarehouses.ts

@@ -136,6 +136,14 @@ export function useAllWarehouseZones() {
   });
 }
 
+/** Live per-zone occupancy for the heatmap (optionally scoped to one yard). */
+export function useZoneOccupancy(yardId?: string) {
+  return useQuery({
+    queryKey: ['warehouse-zones', 'occupancy', yardId ?? 'all'],
+    queryFn: () => warehouseService.zoneOccupancy(yardId).then((r) => r.data),
+  });
+}
+
 export function useCreateZone() {
   const qc = useQueryClient();
   return useMutation({