update database

lib/features/cart/domain/entities/cart.dart

@@ -0,0 +1,92 @@
+/// Domain Entity: Cart
+///
+/// Represents a shopping cart for a user.
+library;
+
+/// Cart Entity
+///
+/// Contains cart-level information:
+/// - User ID
+/// - Total amount
+/// - Sync status
+/// - Timestamps
+class Cart {
+  /// Unique cart identifier
+  final String cartId;
+
+  /// User ID who owns this cart
+  final String userId;
+
+  /// Total cart amount
+  final double totalAmount;
+
+  /// Whether cart is synced with backend
+  final bool isSynced;
+
+  /// Last modification timestamp
+  final DateTime lastModified;
+
+  /// Cart creation timestamp
+  final DateTime createdAt;
+
+  const Cart({
+    required this.cartId,
+    required this.userId,
+    required this.totalAmount,
+    required this.isSynced,
+    required this.lastModified,
+    required this.createdAt,
+  });
+
+  /// Check if cart is empty
+  bool get isEmpty => totalAmount == 0;
+
+  /// Check if cart needs sync
+  bool get needsSync => !isSynced;
+
+  /// Copy with method for immutability
+  Cart copyWith({
+    String? cartId,
+    String? userId,
+    double? totalAmount,
+    bool? isSynced,
+    DateTime? lastModified,
+    DateTime? createdAt,
+  }) {
+    return Cart(
+      cartId: cartId ?? this.cartId,
+      userId: userId ?? this.userId,
+      totalAmount: totalAmount ?? this.totalAmount,
+      isSynced: isSynced ?? this.isSynced,
+      lastModified: lastModified ?? this.lastModified,
+      createdAt: createdAt ?? this.createdAt,
+    );
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+
+    return other is Cart &&
+        other.cartId == cartId &&
+        other.userId == userId &&
+        other.totalAmount == totalAmount &&
+        other.isSynced == isSynced;
+  }
+
+  @override
+  int get hashCode {
+    return Object.hash(
+      cartId,
+      userId,
+      totalAmount,
+      isSynced,
+    );
+  }
+
+  @override
+  String toString() {
+    return 'Cart(cartId: $cartId, userId: $userId, totalAmount: $totalAmount, '
+        'isSynced: $isSynced, lastModified: $lastModified)';
+  }
+}