fix: 修复前台获取新闻时验证码验证失败的问题

问题原因：fetch请求缺少credentials选项，导致浏览器不发送session cookie
解决方案：添加credentials: 'same-origin'确保发送session cookie

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

templates/detail_new.html

@@ -1036,6 +1036,7 @@ function loadNewsWithCaptcha(siteCode, captcha) {
     // 调用新闻获取API
     fetch(`/api/fetch-news/${siteCode}`, {
         method: 'POST',
+        credentials: 'same-origin',  // 确保发送session cookie
         headers: {
             'Content-Type': 'application/json'
         },