refactor(dto): type duration_minutes as int to match backend

lib/features/tests/catalog/data/dto/testing_catalog_item_dto.dart

@@ -16,9 +16,9 @@ class TestingCatalogItemDto {
   /// Short testing description.
   final String description;
 
-  /// Approximate duration in minutes provided by the backend.
+  /// Approximate duration in minutes.
   @JsonKey(name: 'duration_minutes')
-  final String durationMinutes;
+  final int durationMinutes;
 
   /// Testing image path or URL.
   final String image;

lib/features/tests/catalog/data/mappers/testing_catalog_mapper.dart

@@ -11,7 +11,7 @@ extension TestingCatalogItemMapper on TestingCatalogItemDto {
     id: id,
     title: title,
     description: description,
-    durationMinutes: int.tryParse(durationMinutes.trim()) ?? 0,
+    durationMinutes: durationMinutes,
     imageUrl: normalizeTestingImageUrl(image),
     categories: categories.map((category) => category.toEntity()).toList(growable: false),
     exercisesCount: exercisesCount,

lib/features/workouts/data/dto/workout_summary_dto.dart

@@ -14,9 +14,9 @@ class WorkoutSummaryDto {
   /// Short workout description.
   final String description;
 
-  /// Workout duration in minutes provided by the backend.
+  /// Workout duration in minutes.
   @JsonKey(name: 'duration_minutes')
-  final String durationMinutes;
+  final int durationMinutes;
 
   /// Workout preview image path or URL.
   final String? image;

lib/features/workouts/data/mappers/workout_details_mapper.dart

@@ -19,7 +19,7 @@ extension WorkoutDetailsMapper on WorkoutDetailsDataDto {
       type: WorkoutDetailsItemType.workout,
       title: workout.title,
       description: workout.description,
-      durationMinutes: _parseDurationMinutes(workout.durationMinutes),
+      durationMinutes: workout.durationMinutes,
       imageUrl: normalizeWorkoutImageUrl(workout.image ?? ''),
     ),
   ];
@@ -29,5 +29,3 @@ int _durationSecondsToMinutes(int seconds) {
   if (seconds <= 0) return 0;
   return (seconds / 60).ceil();
 }
-
-int _parseDurationMinutes(String rawValue) => int.tryParse(rawValue.trim()) ?? 0;

lib/features/workouts/data/mappers/workout_overview_mapper.dart

@@ -11,9 +11,7 @@ extension WorkoutOverviewMapper on UserWorkoutOverviewItemDto {
     isBlockedByActiveWorkout: hasActive && status != 'started',
     title: workout.title,
     description: workout.description,
-    durationMinutes: _parseDurationMinutes(workout.durationMinutes),
+    durationMinutes: workout.durationMinutes,
     imageUrl: normalizeWorkoutImageUrl(workout.image ?? ''),
   );
 }
-
-int _parseDurationMinutes(String rawValue) => int.tryParse(rawValue.trim()) ?? 0;

test/features/tests/catalog/data/mappers/testing_catalog_mapper_test.dart

@@ -8,7 +8,7 @@ void main() {
   group('TestingCatalogItemMapper.toEntity', () {
     test('maps dto to entity with normalized relative image url', () {
       final dto = createTestingCatalogItemDto(
-        durationMinutes: '15',
+        durationMinutes: 15,
         image: 'tests/balance.jpg',
       );
 
@@ -55,13 +55,5 @@ void main() {
 
       expect(entity.imageUrl, isEmpty);
     });
-
-    test('maps invalid duration to 0', () {
-      final dto = createTestingCatalogItemDto(durationMinutes: 'not_a_number');
-
-      final entity = dto.toEntity();
-
-      expect(entity.durationMinutes, 0);
-    });
   });
 }

test/features/tests/catalog/support/testings_dto_fixtures.dart

@@ -19,7 +19,7 @@ TestingCatalogItemDto createTestingCatalogItemDto({
   int id = 1,
   String title = 'Расширенная диагностика',
   String description = 'Описание теста',
-  String durationMinutes = '20',
+  int durationMinutes = 20,
   String image = 'test.jpg',
   List<TestingCategoryDto>? categories,
   int exercisesCount = 4,
@@ -45,7 +45,7 @@ TestingsResponseDto createTestingsResponseDto() => TestingsResponseDto(
     createTestingCatalogItemDto(
       id: 2,
       title: 'Быстрая проверка',
-      durationMinutes: '10',
+      durationMinutes: 10,
       image: 'https://cdn.example.com/testing-2.jpg',
       categories: [
         createTestingCategoryDto(id: 3, name: 'Гибкость'),

test/features/workouts/support/workouts_dto_fixtures.dart

@@ -29,7 +29,7 @@ WorkoutsResponseDto createWorkoutsResponseDto() => WorkoutsResponseDto(
           id: 1,
           title: 'title',
           description: 'description',
-          durationMinutes: '1',
+          durationMinutes: 1,
           image: 'image.png',
         ),
         status: 'started',
@@ -42,7 +42,7 @@ WorkoutsResponseDto createWorkoutsResponseDto() => WorkoutsResponseDto(
           id: 2,
           title: 'title',
           description: 'description',
-          durationMinutes: '2',
+          durationMinutes: 2,
           image: 'image_2.png',
         ),
         status: 'assigned',
@@ -78,7 +78,7 @@ WorkoutDetailsResponseDto createWorkoutDetailsResponseDto({
       id: 1,
       title: 'title',
       description: 'description',
-      durationMinutes: '1',
+      durationMinutes: 1,
       image: 'test.png',
     ),
   ),