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-skills.njk

@@ -18,7 +18,7 @@
       </h3>
       <div class="flex flex-wrap gap-1.5">
         {% for skill in items %}
-        <span class="text-xs px-2 py-1 bg-primary-50 dark:bg-primary-900/30 text-primary-700 dark:text-primary-300 rounded-full">
+        <span class="text-xs px-2 py-1 bg-accent-50 dark:bg-accent-900/30 text-accent-700 dark:text-accent-300 rounded-full">
           {{ skill }}
         </span>
         {% endfor %}