simplify: dedupe boilerplate and remove dead code across all layers

lib/api/marianumconnect/queries/get_ticker_nav/get_ticker_nav.dart

@@ -6,10 +6,6 @@ import 'get_ticker_nav_response.dart';
 class GetTickerNav extends MarianumConnectQuery {
   GetTickerNav({super.dio});
 
-  Future<TickerNavResponse> run() => guard(() async {
-    final response = await dio.get<Map<String, dynamic>>(
-      endpoint('ticker/pages'),
-    );
-    return TickerNavResponse.fromJson(response.data!);
-  });
+  Future<TickerNavResponse> run() =>
+      getObject('ticker/pages', TickerNavResponse.fromJson);
 }