feat: 添加商户规则支持和用户实体扩展

- 在 `UserEntity` 中添加 `canteenId` 字段以支持离线模式
- 新增 `ServiceMchRule` 模型和相关 API 方法用于获取商户规则
- 更新 `CanteenExtraPriceSetting` 模型以包含商户规则列表
- 在 `CanteenProductController` 中添加获取商户规则的逻辑
- 更新数据库表结构以支持 `canteenId` 字段

lib/common/services/database/entity/user_entity.dart

@@ -35,6 +35,9 @@ class UserEntity extends Equatable {
   /// 钱包余额
   int? walletBalance;
 
+  /// 用户所属的商户id(主要用于机器的离线模式)
+  int? canteenId;
+
   /// 创建时间
   DateTime? createTime;
 
@@ -51,6 +54,7 @@ class UserEntity extends Equatable {
     this.walletId,
     this.walletTypeId,
     this.walletBalance,
+    this.canteenId,
     this.createTime,
     this.updateTime,
   });

lib/common/services/database/entity/user_entity.g.dart

@@ -16,6 +16,7 @@ UserEntity _$UserEntityFromJson(Map<String, dynamic> json) => UserEntity(
       walletId: json['walletId'] as String?,
       walletTypeId: json['walletTypeId'] as String?,
       walletBalance: (json['walletBalance'] as num?)?.toInt(),
+      canteenId: (json['canteenId'] as num?)?.toInt(),
       createTime: json['createTime'] == null
           ? null
           : DateTime.parse(json['createTime'] as String),
@@ -35,6 +36,7 @@ Map<String, dynamic> _$UserEntityToJson(UserEntity instance) =>
       'walletId': instance.walletId,
       'walletTypeId': instance.walletTypeId,
       'walletBalance': instance.walletBalance,
+      'canteenId': instance.canteenId,
       'createTime': instance.createTime?.toIso8601String(),
       'updateTime': instance.updateTime?.toIso8601String(),
     };