Enhance winner management with localStorage updates

Refactored winner storage logic by introducing `clearWinnerLS` and replacing outdated functions with `getWinnerLS` and `setWinnerLS`. Added a `WinnerBadge` component to display the winner's status and updated game lifecycle handling to ensure proper winner reset and management.

frontend/src/components/WinnerBadge.jsx

@@ -0,0 +1,28 @@
+// frontend/src/utils/winnerStorage.js
+
+function winnerKey(gameId) {
+  return `winner:${gameId}`;
+}
+
+export function getWinnerLS(gameId) {
+  if (!gameId) return "";
+  try {
+    return localStorage.getItem(winnerKey(gameId)) || "";
+  } catch {
+    return "";
+  }
+}
+
+export function setWinnerLS(gameId, name) {
+  if (!gameId) return;
+  try {
+    localStorage.setItem(winnerKey(gameId), (name || "").trim());
+  } catch {}
+}
+
+export function clearWinnerLS(gameId) {
+  if (!gameId) return;
+  try {
+    localStorage.removeItem(winnerKey(gameId));
+  } catch {}
+}