fix(article): 移除 recordRead 中重复的 minSeconds 变量声明

cfc-backend/src/main/java/com/etotem/cfc/service/ArticleService.java

@@ -219,8 +219,6 @@ public class ArticleService {
         }
 
         // 4. Check reading duration threshold
-        int minSeconds = getArticleReadingMinSeconds();
-
         if (durationSeconds < minSeconds) {
             result.put("belowThreshold", true);
             result.put("minSeconds", minSeconds);