更新会员服务中的VIP等级逻辑

src/services/member.service.ts

@@ -281,7 +281,7 @@ export class MemberService {
 
   async checkVipExpireTime(member: Member): Promise<void> {
     if (member.vipExpireTime && member.vipExpireTime < new Date()) {
-      member.vipLevel = VipLevel.GUEST
+      member.vipLevel = VipLevel.FREE
       await this.update(member.id, member)
     }
   }