fix: 修复日期显示NaN年NaN月NaN日的问题

- formatDate兼容date和createdAt两种字段名
- 增加空值和无效日期防御
- 同步news.json分类数据（之前category全为null）

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pages/blog/[id].vue

@@ -14,7 +14,7 @@
             <!-- 文章元信息 -->
             <div class="article-meta">
               <span class="article-category">{{ article.category }}</span>
-              <span class="article-date">{{ formatDate(article.date) }}</span>
+              <span class="article-date">{{ formatDate(article.date || article.createdAt) }}</span>
               <span class="article-author">作者：{{ article.author }}</span>
             </div>
 
@@ -230,7 +230,9 @@ const nextArticle = computed(() => currentIndex.value < allArticles.value.length
 const otherArticles = allArticles
 
 function formatDate(dateStr) {
-  const d = new Date(dateStr)
+  if (!dateStr) return ''
+  const d = new Date(dateStr.includes('T') ? dateStr : dateStr + 'T00:00:00')
+  if (isNaN(d.getTime())) return ''
   return `${d.getFullYear()}年${d.getMonth() + 1}月${d.getDate()}日`
 }
 </script>

pages/blog/index.vue

@@ -51,7 +51,7 @@
               </div>
               <div class="blog-card__body">
                 <div class="blog-card__meta">
-                  <span class="blog-card__date">{{ formatDate(article.date) }}</span>
+                  <span class="blog-card__date">{{ formatDate(article.date || article.createdAt) }}</span>
                   <span class="blog-card__author">{{ article.author }}</span>
                 </div>
                 <h2 class="blog-card__title">{{ article.title }}</h2>
@@ -136,7 +136,9 @@ function getCategoryCount(key) {
 }
 
 function formatDate(dateStr) {
-  const d = new Date(dateStr)
+  if (!dateStr) return ''
+  const d = new Date(dateStr.includes('T') ? dateStr : dateStr + 'T00:00:00')
+  if (isNaN(d.getTime())) return ''
   return `${d.getFullYear()}年${d.getMonth() + 1}月${d.getDate()}日`
 }
 </script>