feat:"初始化仓库，并更新基础代码。"

lib/models/transaction_model.dart

@@ -0,0 +1,47 @@
+class TransactionModel {
+  final String id;
+  final double amount;
+  final String type; // 'income' or 'expense'
+  final int categoryId;
+  final DateTime date;
+  final String? note;
+  final DateTime createdAt;
+  final DateTime updatedAt;
+
+  TransactionModel({
+    required this.id,
+    required this.amount,
+    required this.type,
+    required this.categoryId,
+    required this.date,
+    this.note,
+    required this.createdAt,
+    required this.updatedAt,
+  });
+
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'amount': amount,
+      'type': type,
+      'categoryId': categoryId,
+      'date': date.millisecondsSinceEpoch,
+      'note': note,
+      'createdAt': createdAt.millisecondsSinceEpoch,
+      'updatedAt': updatedAt.millisecondsSinceEpoch,
+    };
+  }
+
+  factory TransactionModel.fromMap(Map<String, dynamic> map) {
+    return TransactionModel(
+      id: map['id'],
+      amount: map['amount'],
+      type: map['type'],
+      categoryId: map['categoryId'],
+      date: DateTime.fromMillisecondsSinceEpoch(map['date']),
+      note: map['note'],
+      createdAt: DateTime.fromMillisecondsSinceEpoch(map['createdAt']),
+      updatedAt: DateTime.fromMillisecondsSinceEpoch(map['updatedAt']),
+    );
+  }
+}