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/screens/common/app_layout.dart

@@ -1137,6 +1137,14 @@ class SidebarMenu extends StatelessWidget {
                     ),
                   ],
                 ),
+
+                _buildMenuItem(
+                  icon: Icons.calendar_month_outlined,
+                  title: '임대 관리',
+                  route: Routes.rent,
+                  isActive: currentRoute == Routes.rent,
+                  badge: null,
+                ),
                 
 
                 if (!collapsed) ...[
@@ -1376,6 +1384,8 @@ class SidebarMenu extends StatelessWidget {
         return Icons.factory;
       case Icons.category_outlined:
         return Icons.category;
+      case Icons.calendar_month_outlined:
+        return Icons.calendar_month;
       default:
         return outlinedIcon;
     }