feat: replace all primary (blue) with contextual colors across entire theme

Eliminate monotonous blue by replacing ~290 primary- references in 60 files
with semantically appropriate colors:

- accent (teal): links, CTAs, buttons, tabs, focus rings, spinners
- purple: Funkwhale/music, photos, Mastodon/fediverse
- surface (neutral): GitHub, dates/metadata, info boxes
- amber: bookmarks, blogroll categories
- red: likes
- green: reposts
- sky: replies
- orange: RSS/feeds, podcasts
- #0085ff: Bluesky brand
- #a730b8: Mastodon brand

Also updates prose link colors in tailwind.config.js, pagefind UI
primary color to teal, and client-side JS color references.

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

_includes/components/sections/cv-projects.njk

@@ -15,7 +15,7 @@
 
   <div class="grid grid-cols-1 sm:grid-cols-2 gap-4">
     {% for item in cv.projects | head(maxItems) %}
-    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 hover:border-primary-400 dark:hover:border-primary-600 transition-colors overflow-hidden">
+    <div class="bg-white dark:bg-surface-800 rounded-lg border border-surface-200 dark:border-surface-700 hover:border-accent-400 dark:hover:border-accent-600 transition-colors overflow-hidden">
       {# Summary row — always visible, clickable #}
       <button
         class="w-full p-4 flex items-center justify-between gap-2 cursor-pointer text-left hover:bg-surface-50 dark:hover:bg-surface-700/50 transition-colors"
@@ -25,7 +25,7 @@
         <div class="flex items-center gap-2 min-w-0 flex-1">
           <h3 class="font-semibold text-surface-900 dark:text-surface-100 truncate">
             {% if item.url %}
-            <a href="{{ item.url }}" class="hover:text-primary-600 dark:hover:text-primary-400" @click.stop>{{ item.name }}</a>
+            <a href="{{ item.url }}" class="hover:text-accent-600 dark:hover:text-accent-400" @click.stop>{{ item.name }}</a>
             {% else %}
             {{ item.name }}
             {% endif %}