adds syncing

lib/models/ingredient.dart

@@ -1,14 +1,26 @@
+import 'sync_enums.dart';
+
 class Ingredient {
   final int? id;
   final String name; // e.g., "Vitamin K2", "Vitamin D3"
   final double amount; // e.g., 75, 20
   final String unit; // e.g., "mcg", "mg", "IU"
 
+  // Sync metadata
+  final String syncId;
+  final DateTime lastModified;
+  final SyncStatus syncStatus;
+  final bool isDeleted;
+
   const Ingredient({
     this.id,
     required this.name,
     required this.amount,
     required this.unit,
+    required this.syncId,
+    required this.lastModified,
+    this.syncStatus = SyncStatus.pending,
+    this.isDeleted = false,
   });
 
   Map<String, dynamic> toMap() {
@@ -17,6 +29,10 @@ class Ingredient {
       'name': name,
       'amount': amount,
       'unit': unit,
+      'syncId': syncId,
+      'lastModified': lastModified.toIso8601String(),
+      'syncStatus': syncStatus.name,
+      'isDeleted': isDeleted ? 1 : 0,
     };
   }
 
@@ -26,6 +42,17 @@ class Ingredient {
       name: map['name'],
       amount: map['amount']?.toDouble() ?? 0.0,
       unit: map['unit'],
+      syncId: map['syncId'] ?? '',
+      lastModified: map['lastModified'] != null
+          ? DateTime.parse(map['lastModified'])
+          : DateTime.now(),
+      syncStatus: map['syncStatus'] != null
+          ? SyncStatus.values.firstWhere(
+              (e) => e.name == map['syncStatus'],
+              orElse: () => SyncStatus.pending,
+            )
+          : SyncStatus.pending,
+      isDeleted: (map['isDeleted'] ?? 0) == 1,
     );
   }
 
@@ -34,12 +61,20 @@ class Ingredient {
     String? name,
     double? amount,
     String? unit,
+    String? syncId,
+    DateTime? lastModified,
+    SyncStatus? syncStatus,
+    bool? isDeleted,
   }) {
     return Ingredient(
       id: id ?? this.id,
       name: name ?? this.name,
       amount: amount ?? this.amount,
       unit: unit ?? this.unit,
+      syncId: syncId ?? this.syncId,
+      lastModified: lastModified ?? this.lastModified,
+      syncStatus: syncStatus ?? this.syncStatus,
+      isDeleted: isDeleted ?? this.isDeleted,
     );
   }
 
@@ -54,11 +89,12 @@ class Ingredient {
     return other is Ingredient &&
         other.name == name &&
         other.amount == amount &&
-        other.unit == unit;
+        other.unit == unit &&
+        other.syncId == syncId;
   }
 
   @override
   int get hashCode {
-    return name.hashCode ^ amount.hashCode ^ unit.hashCode;
+    return name.hashCode ^ amount.hashCode ^ unit.hashCode ^ syncId.hashCode;
   }
 }