HEL-203: 修复原因弹窗作用域、首屏断档与表单 reset

将 openModal/closeModal 提升为顶层唯一定义，公司端启动即加载断档提醒，
并在 await 前提取表单引用；补充 Playwright 两端冒烟与源码契约测试。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

web/admin.html

@@ -962,6 +962,6 @@
       </div>
     </div>
     <div class="toast-region" id="toastRegion" aria-live="polite"></div>
-    <script src="app.js?v=9"></script>
+    <script src="app.js?v=13"></script>
   </body>
 </html>