feat(notification-outbox): CommunicationService per-site KPI accessor

src/ScadaLink.Communication/CommunicationService.cs

@@ -281,6 +281,13 @@ public class CommunicationService
         return await GetNotificationOutbox().Ask<NotificationKpiResponse>(
             request, _options.QueryTimeout, cancellationToken);
     }
+
+    public async Task<PerSiteNotificationKpiResponse> GetPerSiteNotificationKpisAsync(
+        PerSiteNotificationKpiRequest request, CancellationToken cancellationToken = default)
+    {
+        return await GetNotificationOutbox().Ask<PerSiteNotificationKpiResponse>(
+            request, _options.QueryTimeout, cancellationToken);
+    }
 }
 
 /// <summary>