feat(dependencies): add rxdart package and improve string extension methods for better handling of empty strings and gender parsing

test/features/diary/models/create_day_model_test.dart

@@ -0,0 +1,23 @@
+import 'package:eatvio_app/features/diary/models/create_day_model.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('CreateDayModel', () {
+    test('создает CreateDayModel с правильными значениями', () {
+      final model = CreateDayModel(day: '2024-01-01');
+
+      expect(model.day, '2024-01-01');
+    });
+
+    test('fromJson создает CreateDayModel из JSON', () {
+      final json = {
+        'day': '2024-01-01',
+      };
+
+      final model = CreateDayModel.fromJson(json);
+
+      expect(model.day, '2024-01-01');
+    });
+  });
+}
+