refactor: 金币默认值改为数据库层面设置

- UserInfo实体类coins字段添加默认值DEFAULT 3
- 移除前后端硬编码的金币默认值
- 新增consumeCoins API接口用于金币消耗
- coinUtils.js改为从服务器获取金币数据
- 所有测算页面checkCoinsAndConsume改为异步调用
- VIP用户测算不消耗金币

src/main/java/xuan/entity/UserInfo.java

@@ -31,6 +31,7 @@ public class UserInfo {
     
     private Integer vipLevel;
     
+    @Column(columnDefinition = "INT DEFAULT 3")
     private Integer coins;
     
     private Integer streakDays;
@@ -45,7 +46,6 @@ public class UserInfo {
         createTime = LocalDateTime.now();
         updateTime = createTime;
         vipLevel = 0;
-        coins = 3;
         streakDays = 0;
     }