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

digest-index.njk

@@ -15,15 +15,15 @@ permalink: "digest/{% if pagination.pageNumber > 0 %}page/{{ pagination.pageNumb
 <div>
   <h1 class="text-2xl sm:text-3xl font-bold text-surface-900 dark:text-surface-100 mb-2">Weekly Digest</h1>
   <p class="text-surface-600 dark:text-surface-400 mb-6 sm:mb-8">
-    A weekly summary of all posts. Subscribe via <a href="/digest/feed.xml" class="text-primary-600 dark:text-primary-400 hover:underline">RSS</a> for one update per week.
+    A weekly summary of all posts. Subscribe via <a href="/digest/feed.xml" class="text-orange-600 dark:text-orange-400 hover:underline">RSS</a> for one update per week.
   </p>
 
   {% if paginatedDigests.length > 0 %}
   <ul class="space-y-4">
     {% for d in paginatedDigests %}
-    <li class="p-4 bg-white dark:bg-surface-800 border border-surface-200 dark:border-surface-700 rounded-lg hover:border-primary-300 dark:hover:border-primary-600 transition-colors">
+    <li class="p-4 bg-white dark:bg-surface-800 border border-surface-200 dark:border-surface-700 rounded-lg hover:border-accent-300 dark:hover:border-accent-600 transition-colors">
       <a href="/digest/{{ d.slug }}/" class="block">
-        <h2 class="font-semibold text-surface-900 dark:text-surface-100 hover:text-primary-600 dark:hover:text-primary-400">
+        <h2 class="font-semibold text-surface-900 dark:text-surface-100 hover:text-accent-600 dark:hover:text-accent-400">
           {{ d.label }}
         </h2>
         <p class="text-sm text-surface-500 dark:text-surface-400 mt-1">