고객사 목록 쿼리스트링 연동 및 공통 JSON 파서 도입

lib/features/approvals/history/data/dtos/approval_history_record_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 'package:superport_v2/features/approvals/data/dtos/approval_dto.dart';
 import 'package:superport_v2/features/approvals/domain/entities/approval.dart';
 
@@ -91,17 +92,17 @@ class ApprovalHistoryRecordDto {
   static PaginatedResult<ApprovalHistoryRecord> 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(ApprovalHistoryRecordDto.fromJson)
         .map((dto) => dto.toEntity())
-        .toList();
+        .toList(growable: false);
 
     return PaginatedResult<ApprovalHistoryRecord>(
       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),
     );
   }
 }