simplify: dedupe boilerplate and remove dead code across all layers

lib/api/marianumconnect/queries/get_ticker/get_ticker.dart

@@ -6,8 +6,6 @@ import 'get_ticker_response.dart';
 class GetTicker extends MarianumConnectQuery {
   GetTicker({super.dio});
 
-  Future<TickerResponse> run() => guard(() async {
-    final response = await dio.get<Map<String, dynamic>>(endpoint('ticker'));
-    return TickerResponse.fromJson(response.data!);
-  });
+  Future<TickerResponse> run() =>
+      getObject('ticker', TickerResponse.fromJson);
 }