refactor: update text form field model to use dynamic value type, enhance condition evaluator for step index extraction, and improve SDK path formatting

packages/chicken/lib/presentation/utils/sdui_extension.dart

@@ -0,0 +1,11 @@
+import 'package:rasadyar_chicken/presentation/widget/sdui/model/sdui_widget.dart';
+import 'package:rasadyar_chicken/presentation/widget/sdui/widgets/stepper/model/stepper_sdui_model.dart';
+
+extension SDUIModelExtensions on SDUIWidgetModel {
+  // چک میکند آیا این ویجت استپر است؟
+  bool get isStepper => this.maybeWhen(stepper: (_, _, _, _) => true, orElse: () => false);
+
+  // دیتای استپر را برمی‌گرداند (اگر استپر باشد)
+  StepperSDUIModel? get stepperData =>
+      maybeWhen(stepper: (data, _, _, _) => data, orElse: () => null);
+}