Add SSDP/UPnP scanner to frontend status displays

Surface the SSDP/UPnP scanner alongside ARP and mDNS: a dedicated card on
the Status screen and a row in the consolidated Status card on Home. Mirrors
the existing mDNS implementation and reuses the generic ScannerStatusCard and
PolledValue infrastructure. Also maps the 'Ssdp' device-event scanner to the
"SSDP/UPnP" label.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/utils/oott_api.dart

@@ -8,6 +8,7 @@ import 'package:frontend/utils/backend_reachability.dart';
 import 'package:frontend/utils/pref_utils.dart';
 import '../model/arp_scanner_status.dart';
 import '../model/mdns_scanner_status.dart';
+import '../model/ssdp_scanner_status.dart';
 import '../model/device.dart';
 import '../model/device_event.dart';
 import '../model/device_summary.dart';
@@ -311,6 +312,16 @@ class BackendAPI {
     return MdnsScannerStatus.fromJson(response.data as Map<String, dynamic>);
   }
 
+  Future<SsdpScannerStatus> getSsdpScannerStatus({
+    CancelToken? cancelToken,
+  }) async {
+    final response = await _dio.get(
+      '/ssdp_scanner/status',
+      cancelToken: cancelToken,
+    );
+    return SsdpScannerStatus.fromJson(response.data as Map<String, dynamic>);
+  }
+
   Future<({List<Notification> items, bool hasNextPage})> listNotifications(
     bool? isNew, {
     int page = 0,