Add delete button to design approvals page

Allow admins to delete individual design submissions to clean up test data.
Includes confirmation dialog and reloads page on successful deletion.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/components/DeleteDesignButton.tsx

@@ -0,0 +1,39 @@
+'use client';
+
+import { useState } from 'react';
+
+export default function DeleteDesignButton({ designId }: { designId: string }) {
+  const [deleting, setDeleting] = useState(false);
+
+  const handleDelete = async (e: React.MouseEvent) => {
+    e.preventDefault();
+    e.stopPropagation();
+
+    if (!confirm('Delete this design? This cannot be undone.')) return;
+
+    setDeleting(true);
+    try {
+      const res = await fetch(`/api/designs/${designId}`, { method: 'DELETE' });
+      if (res.ok) {
+        window.location.reload();
+      } else {
+        alert('Failed to delete design');
+        setDeleting(false);
+      }
+    } catch (err) {
+      console.error('Error deleting design:', err);
+      alert('Error deleting design');
+      setDeleting(false);
+    }
+  };
+
+  return (
+    <button
+      onClick={handleDelete}
+      disabled={deleting}
+      className="border border-line px-3 py-2 text-sm text-muted hover:border-ink hover:text-ink disabled:opacity-50"
+    >
+      {deleting ? 'Deleting…' : 'Delete'}
+    </button>
+  );
+}