fix(新闻详情): 作者为空时隐藏作者图标

当文章没有作者信息时，隐藏作者图标，避免显示空的作者信息。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

@@ -13,7 +13,7 @@
         <div class="article-meta">
         <div class="article-meta">
           <div class="meta-info">
           <div class="meta-info">
             <van-icon name="clock-o" /><span class="publish-date">{{ article.publishDate }}</span>
             <van-icon name="clock-o" /><span class="publish-date">{{ article.publishDate }}</span>
-            <van-icon name="manager-o" /><span class="author">{{ article.author }}</span>
+            <van-icon v-if="article.author" name="manager-o" /><span class="author">{{ article.author }}</span>
           </div>
           </div>
         </div>
         </div>
       </div>
       </div>