fix(client): 修复测试 timer 泄漏与编译 warning

- login_screen: Future.delayed 改为 Timer，dispose 时主动取消，
  避免测试框架报 pending timer 错误
- stock_in_form_screen: 移除未使用的 repository import，
  items 去掉无效 ?? [] 死代码（items 字段非空）
- stock_out_form_screen: 同上

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/screens/auth/login_screen.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
@@ -32,6 +34,8 @@ class _LoginScreenState extends ConsumerState<LoginScreen> {
 
   OverlayEntry? _hotelEntry;
   OverlayEntry? _usernameEntry;
+  Timer? _closeHotelTimer;
+  Timer? _closeUsernameTimer;
 
   bool get _hotelShowing => _hotelEntry != null;
   bool get _usernameShowing => _usernameEntry != null;
@@ -46,7 +50,8 @@ class _LoginScreenState extends ConsumerState<LoginScreen> {
             isHotel: true);
       } else if (!_hotelCodeFocus.hasFocus) {
         // 延迟关闭：让候选词的 onTap（pointer-up）先执行，再关闭下拉框
-        Future.delayed(const Duration(milliseconds: 150), _closeHotel);
+        _closeHotelTimer?.cancel();
+        _closeHotelTimer = Timer(const Duration(milliseconds: 150), _closeHotel);
       }
     });
     _usernameFocus.addListener(() {
@@ -54,7 +59,8 @@ class _LoginScreenState extends ConsumerState<LoginScreen> {
         _openDropdown(_usernameLayerLink, _usernameHistory, _usernameCtrl,
             isHotel: false);
       } else if (!_usernameFocus.hasFocus) {
-        Future.delayed(const Duration(milliseconds: 150), _closeUsername);
+        _closeUsernameTimer?.cancel();
+        _closeUsernameTimer = Timer(const Duration(milliseconds: 150), _closeUsername);
       }
     });
   }
@@ -175,6 +181,8 @@ class _LoginScreenState extends ConsumerState<LoginScreen> {
 
   @override
   void dispose() {
+    _closeHotelTimer?.cancel();
+    _closeUsernameTimer?.cancel();
     _hotelEntry?.remove();
     _usernameEntry?.remove();
     _shopCodeCtrl.dispose();