feat: Implement UTC conversion for order date and time serialization in order use cases

apps/mobile/packages/features/staff/shifts/lib/src/data/repositories_impl/shifts_repository_impl.dart

@@ -36,8 +36,8 @@ class ShiftsRepositoryImpl implements ShiftsRepositoryInterface {
     final ApiResponse response = await _apiService.get(
       StaffEndpoints.shiftsAssigned,
       params: <String, dynamic>{
-        'startDate': start.toIso8601String(),
-        'endDate': end.toIso8601String(),
+        'startDate': start.toUtc().toIso8601String(),
+        'endDate': end.toUtc().toIso8601String(),
       },
     );
     final List<dynamic> items = _extractItems(response.data);