fix(api): improve security and performance in leaderboard and rooms

app/api/rooms/route.ts

@@ -55,7 +55,7 @@ function generateCode(): string {
 }
 
 function generatePlayerId(): string {
-  return Math.random().toString(36).slice(2, 10);
+  return crypto.randomUUID();
 }
 
 // Nettoie les rooms inactives depuis plus de 2h