Refactor media upload handling in MediaPanel: remove direct upload logic and integrate useUploadStore for file enqueueing. Update translations for upload status and add UploadSnackbar component to display upload notifications in the UI.

frontend/src/routes/__root.tsx

@@ -7,6 +7,7 @@ import { bootstrapSession, logout, clearSession } from '@/features/auth/api'
 import { useTheme } from '@/theme/ThemeProvider'
 import { setLanguage } from '@/shared/lib/i18n'
 import { cn } from '@/shared/lib/cn'
+import { UploadSnackbar } from '@/features/admin/media/UploadSnackbar'
 
 export const Route = createRootRoute({ component: RootLayout })
 
@@ -131,6 +132,8 @@ function RootLayout() {
       <main className={cn('mx-auto w-full max-w-5xl flex-1 px-4 py-8')}>
         <Outlet />
       </main>
+
+      <UploadSnackbar />
     </div>
   )
 }