style: fix admin table padding — edge-to-edge on mobile, no right pad on desktop

Mobile: remove horizontal padding so tables fill full width with top/bottom
borders only. Desktop: keep left padding, table extends to right edge.

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

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

@@ -37,15 +37,15 @@
   }
 </script>
 
-<div class="p-3 sm:p-6">
-  <div class="flex items-center justify-between mb-6">
+<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">{$_("admin.videos.title")}</h1>
     <Button href="/admin/videos/new">
       <span class="icon-[ri--add-line] h-4 w-4 mr-1"></span>{$_("admin.videos.new_video")}
     </Button>
   </div>
 
-  <div class="rounded-lg border border-border/40 overflow-x-auto">
+  <div class="sm:rounded-lg border-y sm:border border-border/40 overflow-x-auto">
     <table class="w-full text-sm">
       <thead class="bg-muted/30">
         <tr>