feat: implement design system — domain colors, date typography, interaction states, CV family colors

Apply the collaboratively-written design system from .interface-design/system.md:

- Domain color map: Social pages (rose), Code pages (emerald), Reading pages
  (orange), Music pages (purple) replace generic accent tokens
- Font-mono on all <time> elements via global CSS rule + wrap 7 non-<time> dates
- Shadow standardization: replace hover:shadow-lg with border-hover on news cards
- Active states: scale(0.97) press feedback on buttons and pagination links
- Gradient cleanup: remove to-white gradient on github featured project cards
- CV Skills & Interests: cycle through 8 distinct colors per family category
  (amber, emerald, sky, rose, purple, orange, teal, indigo) on both CV page
  and homepage
- Update system.md with refined palette documentation and domain color spec

Files: 19 changed across templates, CSS, and design documentation

Confab-Link: http://localhost:8080/sessions/bd3f7012-c703-47e9-bfe2-2ad04ce1842d

likes.njk

@@ -25,10 +25,10 @@ permalink: "likes/{% if pagination.pageNumber > 0 %}page/{{ pagination.pageNumbe
   {% if paginatedLikes.length > 0 %}
   <ul class="post-list">
     {% for post in paginatedLikes %}
-    <li class="h-entry post-card border-l-[3px] border-l-red-400 dark:border-l-red-500">
+    <li class="h-entry post-card border-l-[3px] border-l-rose-400 dark:border-l-rose-500">
       <div class="post-header flex items-start gap-3">
         <div class="flex-shrink-0 mt-1">
-          <svg class="w-5 h-5 text-red-500" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
+          <svg class="w-5 h-5 text-rose-500" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
             <path d="M12 21.35l-1.45-1.32C5.4 15.36 2 12.28 2 8.5 2 5.42 4.42 3 7.5 3c1.74 0 3.41.81 4.5 2.09C13.09 3.81 14.76 3 16.5 3 19.58 3 22 5.42 22 8.5c0 3.78-3.4 6.86-8.55 11.54L12 21.35z"/>
           </svg>
         </div>
@@ -62,7 +62,7 @@ permalink: "likes/{% if pagination.pageNumber > 0 %}page/{{ pagination.pageNumbe
             {{ post.templateContent | safe }}
           </div>
           {% endif %}
-          <a class="u-url text-sm text-red-600 dark:text-red-400 hover:underline mt-3 inline-block" href="{{ post.url }}">Permalink</a>
+          <a class="u-url text-sm text-rose-600 dark:text-rose-400 hover:underline mt-3 inline-block" href="{{ post.url }}">Permalink</a>
         </div>
       </div>
     </li>