fix: configure CORS to allow specific origins and enable credentials

backend/server.js

@@ -16,7 +16,12 @@ env.config();
 const app = express();
 const port = 8002;
 
-app.use(cors());
+app.use(
+  cors({
+    origin: ["https://backend.lose.the1s.de", "https://lose.the1s.de"],
+    credentials: true,
+  })
+);
 // Increase body size limits to support large CSV JSON payloads
 app.use(express.urlencoded({ extended: true, limit: "10mb" }));
 app.set("view engine", "ejs");