feat: add pantry management features including repository, providers, and UI integration

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

@@ -0,0 +1,33 @@
+class PantryItem {
+  final int id;
+  final int productId;
+  final String productName;
+  final String? canonicalName;
+  final String? category;
+
+  const PantryItem({
+    required this.id,
+    required this.productId,
+    required this.productName,
+    this.canonicalName,
+    this.category,
+  });
+
+  String get displayName {
+    if (canonicalName != null && canonicalName!.trim().isNotEmpty) {
+      return canonicalName!;
+    }
+    return productName;
+  }
+
+  factory PantryItem.fromJson(Map<String, dynamic> json) {
+    final product = json['product'] as Map<String, dynamic>? ?? {};
+    return PantryItem(
+      id: (json['id'] as num).toInt(),
+      productId: (json['productId'] as num).toInt(),
+      productName: (product['name'] ?? '').toString(),
+      canonicalName: product['canonicalName']?.toString(),
+      category: product['category']?.toString(),
+    );
+  }
+}

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

@@ -0,0 +1,29 @@
+class PantryProduct {
+  final int id;
+  final String name;
+  final String? canonicalName;
+  final String? category;
+
+  const PantryProduct({
+    required this.id,
+    required this.name,
+    this.canonicalName,
+    this.category,
+  });
+
+  String get displayName {
+    if (canonicalName != null && canonicalName!.trim().isNotEmpty) {
+      return canonicalName!;
+    }
+    return name;
+  }
+
+  factory PantryProduct.fromJson(Map<String, dynamic> json) {
+    return PantryProduct(
+      id: (json['id'] as num).toInt(),
+      name: (json['name'] ?? '').toString(),
+      canonicalName: json['canonicalName']?.toString(),
+      category: json['category']?.toString(),
+    );
+  }
+}