feat(pricing): 添加优惠券用户领取数量限制功能

- 新增用户领取数量限制字段 userClaimLimit
- 区分已领取数量 claimedQuantity 和已使用数量 usedQuantity
- 添加用户领取次数统计方法 countUserCouponClaims
- 实现领取上限检查逻辑和错误码 CLAIM_LIMIT_REACHED
- 更新数据库表结构和索引优化建议
- 完善文档说明和版本更新记录

src/main/java/com/ycwl/basic/pricing/mapper/PriceCouponClaimRecordMapper.java

@@ -33,9 +33,16 @@ public interface PriceCouponClaimRecordMapper extends BaseMapper<PriceCouponClai
      */
     @Select("SELECT * FROM price_coupon_claim_record " +
             "WHERE user_id = #{userId} AND coupon_id = #{couponId}")
-    PriceCouponClaimRecord selectUserCouponRecord(@Param("userId") Long userId, 
+    PriceCouponClaimRecord selectUserCouponRecord(@Param("userId") Long userId,
                                                   @Param("couponId") Long couponId);
-    
+
+    /**
+     * 统计用户领取某优惠券的次数（所有状态）
+     */
+    @Select("SELECT COUNT(*) FROM price_coupon_claim_record " +
+            "WHERE user_id = #{userId} AND coupon_id = #{couponId} AND deleted = 0")
+    int countUserCouponClaims(@Param("userId") Long userId, @Param("couponId") Long couponId);
+
     /**
      * 更新优惠券使用状态
      */