feat(design): bento featured grid, theme-aware cards, mono tag chips

- Homepage (EN + ZH) featured section becomes a 2x2 Cyber-Bento grid: OG
  thumbnail at 65%/140px behind a scrim, category badge + metric pill,
  3-line-clamped description, arrow CTA; 1 column under 680px.
- Bento scrim/pill/dot now use theme tokens (--card-veil, --pill-bg,
  --bento-visual-opacity). The original hardcoded dark blend measured
  1.96:1 pill contrast on the light theme; now 6.56 dark / 6.10 light.
- Add the missing @keyframes bento-pulse (the doc claimed a pulsing dot,
  none existed), disabled under prefers-reduced-motion.
- Tag chips: mono face, hairline border, 4px radius; dashed border for
  non-link tags.
- ZH pages: brand links /zh/, in-post category tag links
  /zh/categories/<cat>/ instead of the EN route.
- project-state: B6 shipped note with measured readings; correct the
  prompts-catalog path claim (file is outside the repo).

Measured in headless Chrome at 1280px and 390px, EN + ZH: 4 cards,
2 cols / 1 col, scrollWidth-clientWidth 0, no card overflow, all four
-800.webp thumbs loaded at 800x420.

src/layouts/BaseLayout.astro

@@ -176,7 +176,7 @@ const nav = isZh
   <body>
     <header class="site-header">
       <nav class="nav" aria-label="Main">
-        <a class="brand" href="/">Mr<span class="dot"> Hoelee</span></a>
+        <a class="brand" href={isZh ? '/zh/' : '/'}>Mr<span class="dot"> Hoelee</span></a>
         <a href={isZh ? '/zh/posts/' : '/posts/'}>{nav.posts}</a>
         <a href={isZh ? '/zh/categories/' : '/categories/'}>{nav.categories}</a>
         <a href={isZh ? '/zh/about/' : '/about/'}>{nav.about}</a>