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/controller/UserController.java

@@ -266,4 +266,31 @@ public class UserController {
         }
         return result;
     }
+    
+    @PostMapping("/consumeCoins")
+    public Map<String, Object> consumeCoins(@RequestBody Map<String, Object> params) {
+        Map<String, Object> result = new HashMap<>();
+        try {
+            String userId = params.get("userId").toString();
+            Integer amount = params.get("amount") != null ? Integer.parseInt(params.get("amount").toString()) : 1;
+            String type = params.get("type") != null ? params.get("type").toString() : "unknown";
+            String description = params.get("description") != null ? params.get("description").toString() : "金币消耗";
+            String relatedId = params.get("relatedId") != null ? params.get("relatedId").toString() : null;
+            
+            UserInfo user = userInfoService.consumeCoins(userId, amount, type, description, relatedId);
+            if (user != null) {
+                Map<String, Object> data = new HashMap<>();
+                data.put("coins", user.getCoins());
+                result.put("success", true);
+                result.put("data", data);
+            } else {
+                result.put("success", false);
+                result.put("error", "用户不存在或金币不足");
+            }
+        } catch (Exception e) {
+            result.put("success", false);
+            result.put("error", e.getMessage());
+        }
+        return result;
+    }
 }