refactor(blog): extract blog utilities into shared module

Move common blog functionality like post filtering, sorting and data extraction into a centralized utils module.
Replace Astro.glob with import.meta.glob for better performance.
Update all blog components and pages to use the new utilities.

src/components/blog/CategoryCard.astro

@@ -1,76 +1,42 @@
 ---
-// 导入必要的依赖
 import { type Lang } from '@/i18n/utils';
 import { defaultLang } from '@/i18n/ui';
+import { getBlogBaseUrl, extractCategories } from '@/utils/blog-utils';
 
-// 定义组件属性
+// Define component props
 interface Props {
   lang?: Lang;
   currentCategory?: string;
 }
 
-// 获取组件属性
+// Get component props
 const { lang = defaultLang, currentCategory = '' } = Astro.props;
 
-// 确定基础URL路径
-const baseUrl = lang === defaultLang ? '/blog' : `/${lang}/blog`;
+// Determine base URL path
+const baseUrl = getBlogBaseUrl(lang);
 
-// 读取所有博客文章 - 根据语言选择不同的静态路径
-let allPosts = [];
-if (lang === 'zh') {
-  allPosts = await Astro.glob('/src/pages/zh/blog/posts/*.md');
-} else {
-  allPosts = await Astro.glob('/src/pages/blog/posts/*.md');
-}
+// Read all blog posts - choose different static paths based on language
+const postsGlob = {
+  en: await import.meta.glob('/src/pages/blog/posts/*.md', { eager: true }),
+  zh: await import.meta.glob('/src/pages/zh/blog/posts/*.md', { eager: true })
+};
 
-// 收集所有分类
-const allCategories = new Set<string>();
+// Get posts for current language
+const allPosts = lang === 'zh' ? Object.values(postsGlob.zh) : Object.values(postsGlob.en);
 
-// 处理所有文章的分类
-const categoryMap = new Map<string, string>(); // 存储 categoryId 到 category 名称的映射
+// Extract categories from posts
+const categoryMap = extractCategories(allPosts);
 
-allPosts.forEach(post => {
-  // 处理分类
-  if (post.frontmatter?.category) {
-    const categories = Array.isArray(post.frontmatter.category) 
-      ? post.frontmatter.category 
-      : [post.frontmatter.category];
-    
-    const categoryIds = Array.isArray(post.frontmatter.categoryId) 
-      ? post.frontmatter.categoryId 
-      : post.frontmatter.categoryId ? [post.frontmatter.categoryId] : [];
-    
-    // 如果有 categoryId，则使用 categoryId 和 category 的映射
-    if (categoryIds.length > 0 && categoryIds.length === categories.length) {
-      categories.forEach((cat, index) => {
-        if (cat && categoryIds[index]) {
-          allCategories.add(cat);
-          categoryMap.set(cat, categoryIds[index]);
-        }
-      });
-    } else {
-      // 如果没有 categoryId 或长度不匹配，则使用 category 名称作为 ID
-      categories.forEach(cat => {
-        if (cat) {
-          allCategories.add(cat);
-          categoryMap.set(cat, cat.toLowerCase());
-        }
-      });
-    }
-  }
-});
+// Convert to array and sort
+const categories = Array.from(categoryMap.keys()).sort();
 
-
-// 转换为数组并排序
-const categories = Array.from(allCategories).sort();
-
-// 多语言标题
+// Multilingual titles
 const titles = {
   en: 'Categories',
   zh: '分类'
 };
 
-// 获取当前语言的标题
+// Get title for current language
 const title = titles[lang] || titles[defaultLang];
 ---