bugfix: some minor ui updates for invitation history dialog.

frontend/src/components/ui/common/DialogCloseButton.tsx

@@ -0,0 +1,21 @@
+'use client';
+
+import { X } from 'lucide-react';
+
+type DialogCloseButtonProps = {
+  onClick: () => void;
+  className?: string;
+};
+
+export function DialogCloseButton({ onClick, className = '' }: DialogCloseButtonProps) {
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      className={`shrink-0 rounded-[var(--radius-sm)] p-1.5 text-text-muted hover:text-text-primary hover:bg-background-secondary/80 focus:outline-none focus:ring-2 focus:ring-primary/35 ${className}`}
+      aria-label="Close"
+    >
+      <X className="h-5 w-5 icon-flat" />
+    </button>
+  );
+}