fix product

lib/features/products/domain/entities/product.dart

@@ -24,6 +24,7 @@ class Product {
     this.brand,
     this.unit,
     this.conversionOfSm,
+    this.introAttributes,
     required this.isActive,
     required this.isFeatured,
     this.erpnextItemCode,
@@ -70,6 +71,11 @@ class Product {
   /// Used to calculate: Số viên = Số lượng × conversionOfSm
   final double? conversionOfSm;
 
+  /// Intro attributes (quick reference)
+  /// List of maps with 'code' and 'value' keys
+  /// Example: [{"code": "Size", "value": "120x120"}, {"code": "UOM", "value": "2 viên/hộp"}]
+  final List<Map<String, String>>? introAttributes;
+
   /// Product is active
   final bool isActive;
 
@@ -116,15 +122,25 @@ class Product {
   /// TODO: Implement stock tracking when backend supports it
   bool get isLowStock => false;
 
-  /// Check if product is in stock
-  /// Currently using isActive as proxy
-  bool get inStock => isActive;
-
   /// Get specification value by key
   String? getSpecification(String key) {
     return specifications[key]?.toString();
   }
 
+  /// Get intro attribute value by code
+  String? getIntroAttribute(String code) {
+    if (introAttributes == null) return null;
+
+    try {
+      final attr = introAttributes!.firstWhere(
+        (attr) => attr['code']?.toLowerCase() == code.toLowerCase(),
+      );
+      return attr['value'];
+    } catch (e) {
+      return null;
+    }
+  }
+
   /// Copy with method for creating modified copies
   Product copyWith({
     String? productId,
@@ -140,6 +156,7 @@ class Product {
     String? brand,
     String? unit,
     double? conversionOfSm,
+    List<Map<String, String>>? introAttributes,
     bool? isActive,
     bool? isFeatured,
     String? erpnextItemCode,
@@ -160,6 +177,7 @@ class Product {
       brand: brand ?? this.brand,
       unit: unit ?? this.unit,
       conversionOfSm: conversionOfSm ?? this.conversionOfSm,
+      introAttributes: introAttributes ?? this.introAttributes,
       isActive: isActive ?? this.isActive,
       isFeatured: isFeatured ?? this.isFeatured,
       erpnextItemCode: erpnextItemCode ?? this.erpnextItemCode,