修正Application中处理用户未登录时的交互逻辑

src/Application.java

@@ -41,13 +41,13 @@ public class Application {
    */
   private void handleLoggedOutState() {
     System.out.print("请输入用户名和密码（用空格隔开）: ");
-    String credentials = scanner.nextLine().split("\\s+");
+    String[] credentials = scanner.nextLine().split("\\s+");
     if (credentials.length!= 2) {
       System.out.println("输入格式错误，请重新输入。");
       return;
     }
 
-    authService.login(credentials, credentials)
+    authService.login(credentials[0], credentials[1])
             .ifPresentOrElse(
                     sessionManager::startSession,
                     () -> System.out.println("请输入正确的用户名、密码")