feat(migration): complete WordPress migration and UX refinements

- Migrate historical posts, localized assets, and 103 comments
- Colocate media into posts/<slug>/images/ and remove wp-content
- Add native bilingual support for ai-can-change post (English default, /zh variant)
- Support clean taxonomy routing (/category/:category and /tag/:tag)
- Dynamically populate categories and tags in sitemap.xml
- Fix header scroll padding/margin offsets for anchor and reference links
- Constrain image and media widths to prevent content overflow
- Redesign homepage recent posts to 4 compact editorial cards
- Restore valid binary favicon.ico and high-res icon assets
- Remove placeholder content and sample test comments

server/routes/sitemap.js

@@ -59,6 +59,28 @@ router.get('/sitemap.xml', (req, res) => {
     }
   }
 
+  // Taxonomy archive pages (Categories & Tags)
+  const taxonomy = contentService.getTaxonomy();
+  if (taxonomy.categories && taxonomy.categories.length > 0) {
+    for (const cat of taxonomy.categories) {
+      xml += '  <url>\n';
+      xml += `    <loc>${siteUrl}/category/${encodeURIComponent(cat.name)}</loc>\n`;
+      xml += `    <changefreq>weekly</changefreq>\n`;
+      xml += `    <priority>0.6</priority>\n`;
+      xml += '  </url>\n';
+    }
+  }
+
+  if (taxonomy.tags && taxonomy.tags.length > 0) {
+    for (const tag of taxonomy.tags) {
+      xml += '  <url>\n';
+      xml += `    <loc>${siteUrl}/tag/${encodeURIComponent(tag.name)}</loc>\n`;
+      xml += `    <changefreq>weekly</changefreq>\n`;
+      xml += `    <priority>0.5</priority>\n`;
+      xml += '  </url>\n';
+    }
+  }
+
   xml += '</urlset>';
 
   res.header('Content-Type', 'application/xml; charset=utf-8');