feat(10-04): collapsible panel with flyout, user menu with logout, breadcrumbs and dark mode

- useSidebar: collapsed below 1100px (matchMedia) or by the admin's choice,
  persisted as a boolean under summer-admin.sidebar; the viewport never
  overwrites the stored choice
- SectionPanel collapse and rail expand buttons; SectionFlyout (role menu)
  opens on hover, focus, Enter or ArrowDown on a rail item, closes on Esc or
  about 200 ms after leaving and returns focus to the rail item
- Breadcrumbs with plugin, controller and record crumbs; UserMenu (Reka
  DropdownMenu) with initials, name, role and Wyloguj
- useAuth.logout POSTs /auth/logout, clears user, navigation and settings
  and routes to login even when the call fails
- applyColorScheme toggles .dark from prefers-color-scheme (no toggle, A6)
- newest toast first, 200 ms fade and scale for dialogs and toasts
- one relation-manager type constant in the registry
- shell smoke tests; tests default to a desktop, light matchMedia

admin/src/views/FormView.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { computed, nextTick, onBeforeUnmount, onMounted, ref } from 'vue'
+import { computed, nextTick, onBeforeUnmount, onMounted, ref, watchEffect } from 'vue'
 import { onBeforeRouteLeave, onBeforeRouteUpdate, useRoute, useRouter } from 'vue-router'
 import { ArrowLeft, Trash2 } from '@lucide/vue'
 import { api } from '../api/client'
@@ -28,6 +28,7 @@ import {
 import Button from '../components/ui/Button.vue'
 import ConfirmDialog from '../components/ui/ConfirmDialog.vue'
 import { useConfirm } from '../components/ui/confirm'
+import { clearRecordCrumb, setRecordCrumb } from '../state/useBreadcrumbs'
 import { showToast } from '../state/useToasts'
 
 // Schema-driven create/update form (D-05, D-09, D-10, D-18; design screen
@@ -299,6 +300,10 @@ function onBeforeUnload(event: BeforeUnloadEvent): void {
 onMounted(() => window.addEventListener('beforeunload', onBeforeUnload))
 onBeforeUnmount(() => window.removeEventListener('beforeunload', onBeforeUnload))
 
+// The header's last breadcrumb is this record's title (design: Top header).
+watchEffect(() => setRecordCrumb(loading.value ? '' : title.value))
+onBeforeUnmount(clearRecordCrumb)
+
 void load()
 </script>