feat(playground): add submission footer component

src/app/(app)/playground/@problem/@submission/components/footer.tsx

@@ -0,0 +1,24 @@
+import { cn } from "@/lib/utils";
+
+interface ProblemSubmissionFooterProps {
+  className?: string;
+}
+
+export default function ProblemSubmissionFooter({
+  className,
+  ...props
+}: ProblemSubmissionFooterProps) {
+  return (
+    <footer
+      {...props}
+      className={cn(
+        "h-9 flex flex-none items-center bg-muted px-3 py-2",
+        className
+      )}
+    >
+      <div className="w-full flex items-center justify-center">
+        <span className="truncate">Submission of Two Sum</span>
+      </div>
+    </footer>
+  );
+}