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

views/partials/head.ejs

@@ -33,6 +33,14 @@
     </script>
   <% } %>
 
+  <!-- Site Icons & Favicons -->
+  <link rel="icon" href="/favicon.ico" sizes="any">
+  <link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png">
+  <link rel="icon" type="image/png" sizes="192x192" href="/android-chrome-192x192.png">
+  <link rel="icon" type="image/png" href="/favicon.png">
+  <link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
+  <link rel="shortcut icon" href="/favicon.ico">
+
   <!-- RSS Link -->
   <link rel="alternate" type="application/rss+xml" title="<%= site.title %> RSS Feed" href="/feed">