style: apply gradient to primary buttons in admin area

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/routes/admin/videos/+page.svelte

@@ -40,7 +40,7 @@
 <div class="py-3 sm:py-6 sm:pl-6">
   <div class="flex items-center justify-between mb-6 px-3 sm:px-0">
     <h1 class="text-2xl font-bold">{$_("admin.videos.title")}</h1>
-    <Button href="/admin/videos/new">
+    <Button href="/admin/videos/new" class="bg-gradient-to-r from-primary to-accent hover:from-primary/90 hover:to-accent/90">
       <span class="icon-[ri--add-line] h-4 w-4 mr-1"></span>{$_("admin.videos.new_video")}
     </Button>
   </div>