web: migrate health notifications to js_interop; add browser hook

- Replace dart:js with package:js in health_check_service_web.dart\n- Implement showHealthCheckNotification in web/index.html\n- Pin js dependency to ^0.6.7 for flutter_secure_storage_web compatibility

auth: harden AuthInterceptor + tests

- Allow overrideAuthRepository injection for testing\n- Normalize imports to package: paths\n- Add unit test covering token attach, 401→refresh→retry, and failure path\n- Add integration test skeleton gated by env vars

ui/data: map User.companyName to list column

- Add companyName to domain User\n- Map UserDto.company?.name\n- Render companyName in user_list

cleanup: remove legacy equipment table + unused code; minor warnings

- Remove _buildFlexibleTable and unused helpers\n- Remove unused zipcode details and cache retry constant\n- Fix null-aware and non-null assertions\n- Address child-last warnings in administrator dialog

docs: update AGENTS.md session context

lib/core/navigation/app_navigator.dart

@@ -0,0 +1,18 @@
+import 'package:flutter/widgets.dart';
+
+/// 글로벌 네비게이터 키
+///
+/// - 어디서든(인터셉터 등 BuildContext 없는 곳) 네비게이션이 가능하도록 제공한다.
+/// - 401 등 인증 만료 시 로그인 화면으로의 이동에 사용한다.
+final GlobalKey<NavigatorState> appNavigatorKey = GlobalKey<NavigatorState>();
+
+/// 로그인 화면으로 이동(스택 제거)
+///
+/// - 모든 기존 라우트를 제거하고 '/login'으로 이동한다.
+/// - 네비게이터가 아직 준비되지 않았거나 null일 수 있어 null 세이프 처리한다.
+void navigateToLoginClearingStack() {
+  final navigator = appNavigatorKey.currentState;
+  if (navigator == null) return;
+  navigator.pushNamedAndRemoveUntil('/login', (route) => false);
+}
+