feat: enhance inventory and pantry features with filtering, sorting, and error handling improvements

flutter/lib/features/pantry/domain/pantry_item.dart

@@ -4,6 +4,7 @@ class PantryItem {
   final String productName;
   final String? canonicalName;
   final String? category;
+  final int? categoryId;
 
   const PantryItem({
     required this.id,
@@ -11,6 +12,7 @@ class PantryItem {
     required this.productName,
     this.canonicalName,
     this.category,
+    this.categoryId,
   });
 
   String get displayName {
@@ -28,6 +30,7 @@ class PantryItem {
       productName: (product['name'] ?? '').toString(),
       canonicalName: product['canonicalName']?.toString(),
       category: product['category']?.toString(),
+      categoryId: (product['categoryId'] as num?)?.toInt(),
     );
   }
 }