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/components/form/registry.ts

@@ -33,6 +33,9 @@ export interface FieldControlProps {
   recordId?: number | null
 }
 
+/** The relation manager's field type (design screen 5). */
+export const RELATION_MANAGER = 'relation-manager'
+
 const renderers = new Map<string, Component>([
   ['text', TextField],
   ['textarea', TextareaField],
@@ -41,17 +44,17 @@ const renderers = new Map<string, Component>([
   ['switch', SwitchField],
   ['checkbox', CheckboxField],
   ['relation', RelationField],
-  ['relation-manager', RelationManager],
+  [RELATION_MANAGER, RelationManager],
 ])
 
 /** Types whose control shows the label itself (toggle cards, relation manager). */
-const selfLabelled = new Set<string>(['switch', 'checkbox', 'relation-manager'])
+const selfLabelled = new Set<string>(['switch', 'checkbox', RELATION_MANAGER])
 
 /**
  * Types that need a saved record and hold no form value: never rendered on
  * create, never part of the save body (D-05, design screen 5).
  */
-const recordBound = new Set<string>(['relation-manager'])
+const recordBound = new Set<string>([RELATION_MANAGER])
 
 export function rendererFor(type: string): Component {
   return renderers.get(type) ?? UnsupportedField