고객사 목록 쿼리스트링 연동 및 공통 JSON 파서 도입

lib/features/masters/group/data/dtos/group_dto.dart

@@ -1,4 +1,5 @@
 import 'package:superport_v2/core/common/models/paginated_result.dart';
+import 'package:superport_v2/core/common/utils/json_utils.dart';
 
 import '../../domain/entities/group.dart';
 
@@ -52,16 +53,16 @@ class GroupDto {
   );
 
   static PaginatedResult<Group> parsePaginated(Map<String, dynamic>? json) {
-    final items = (json?['items'] as List<dynamic>? ?? [])
-        .whereType<Map<String, dynamic>>()
+    final rawItems = JsonUtils.extractList(json, keys: const ['items']);
+    final items = rawItems
         .map(GroupDto.fromJson)
         .map((dto) => dto.toEntity())
-        .toList();
+        .toList(growable: false);
     return PaginatedResult<Group>(
       items: items,
-      page: json?['page'] as int? ?? 1,
-      pageSize: json?['page_size'] as int? ?? items.length,
-      total: json?['total'] as int? ?? items.length,
+      page: JsonUtils.readInt(json, 'page', fallback: 1),
+      pageSize: JsonUtils.readInt(json, 'page_size', fallback: items.length),
+      total: JsonUtils.readInt(json, 'total', fallback: items.length),
     );
   }
 }