fix : add missing UI components, maintenance page, fix useRoute warning

- components/ui/SidebarLink.vue and AppTopNav.vue
- infra/prod/maintenance.html
- Remove useRoute() call in useApi onResponseError (fixes middleware warning)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/composables/useApi.ts

@@ -126,10 +126,7 @@ export function useApi(): ApiClient {
           if (!isHandlingUnauthorized) {
             isHandlingUnauthorized = true
             auth.clearSession()
-            const route = useRoute()
-            if (route.path !== '/login') {
-              await navigateTo('/login')
-            }
+            await navigateTo('/login')
             isHandlingUnauthorized = false
           }
         }