docs: polish theme, playground, and reference pages

Improve readability of the docs site with updated light/dark tokens, shared
code-block styling, and playground editors that follow system color scheme.
Skip CookieHub on localhost, serve the browser bundle from theme source, and
use backtick titles on filter/tag reference pages for consistent navigation.

Co-authored-by: Cursor <[email protected]>

docs/themes/navy/layout/partial/head.swig

@@ -35,6 +35,7 @@
   <script src="https://cdn.cookiehub.eu/c2/e8e44c93.js"></script>
   <script type="text/javascript">
   document.addEventListener("DOMContentLoaded", function(event) {
+    if (location.hostname === 'localhost' || location.hostname === '127.0.0.1') return;
     var cpm = {};
     window.cookiehub.load(cpm);
   });