feat(voucher): 实现券码核销功能模块

- 添加券码批次管理和券码管理相关接口和实现
- 新增券码生成、领取、使用等核心业务逻辑
- 实现了全场免费、商品降价、商品打折三种优惠模式
- 添加了券码状态管理和统计功能
- 优化了数据库表结构和索引
- 编写了详细的开发文档和使用示例

src/main/java/com/ycwl/basic/voucher/entity/VoucherCodeEntity.java

@@ -0,0 +1,27 @@
+package com.ycwl.basic.voucher.entity;
+
+import com.baomidou.mybatisplus.annotation.IdType;
+import com.baomidou.mybatisplus.annotation.TableId;
+import com.baomidou.mybatisplus.annotation.TableName;
+import lombok.Data;
+
+import java.util.Date;
+
+@Data
+@TableName("voucher_code")
+public class VoucherCodeEntity {
+    @TableId(value = "id", type = IdType.AUTO)
+    private Long id;
+    
+    private Long batchId;
+    private Long scenicId;
+    private String code;
+    private Integer status;
+    private Long faceId;
+    private Date claimedTime;
+    private Date usedTime;
+    private String remark;
+    private Date createTime;
+    private Integer deleted;
+    private Date deletedAt;
+}