- Implemented configurable public URL rewriting.

What changed:
Added pretty URL helpers/default setting in 
[includes/db.php](/Users/tyemeclifford/Documents/GH/mediaplayer/includes/db.php).
Added root rewrite rules in 
[.htaccess](/Users/tyemeclifford/Documents/GH/mediaplayer/.htaccess):/v/<slug>
/all
/search/<query>

Added Admin → Settings “Public URL Style” toggle in 
[admin/settings.php](/Users/tyemeclifford/Documents/GH/mediaplayer/admin/settings.php), 
defaulting to pretty URLs.
Updated public/player/catalogue/embed/admin preview links to use the 
configured URL style.
Added redirects from legacy ?v= and ?q= URLs to pretty routes when 
rewriting is enabled.
Documented deployment and fallback behavior in 
[README.md](/Users/tyemeclifford/Documents/GH/mediaplayer/README.md).

admin/edit.php

@@ -238,7 +238,7 @@ render_head('Edit Video — Admin', '
       </div>
     </div>
     <nav class="topbar-social">
-      <a class="social-pill" href="../index.php?v=<?= urlencode($video['slug']) ?>" target="_blank">
+      <a class="social-pill" href="<?= h(public_absolute_url(public_video_url($video['slug']))) ?>" target="_blank">
         <svg width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M18 13v6a2 2 0 01-2 2H5a2 2 0 01-2-2V8a2 2 0 012-2h6"/><polyline points="15,3 21,3 21,9"/><line x1="10" y1="14" x2="21" y2="3"/></svg>
         Preview
       </a>