Implement preferred audio languages feature: update site settings to include preferred audio languages, modify related data structures and API endpoints, and enhance media processing to select audio tracks based on user preferences. Update frontend components for managing and displaying these settings.

frontend/src/features/admin/settings/SettingsPanel.tsx

@@ -4,6 +4,7 @@ import { useTranslation } from 'react-i18next'
 import { HttpError } from '@/shared/api/client'
 import { Button } from '@/shared/ui/button'
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/shared/ui/card'
+import { Input } from '@/shared/ui/input'
 import { toast } from '@/shared/ui/toast-store'
 import { getSiteSettings, updateSiteSettings } from './api'
 
@@ -11,6 +12,7 @@ export function SettingsPanel() {
   const { t } = useTranslation()
   const queryClient = useQueryClient()
   const [registrationEnabled, setRegistrationEnabled] = useState(false)
+  const [preferredAudioLanguages, setPreferredAudioLanguages] = useState('')
 
   const { data, isLoading } = useQuery({
     queryKey: ['admin', 'settings'],
@@ -18,11 +20,14 @@ export function SettingsPanel() {
   })
 
   useEffect(() => {
-    if (data) setRegistrationEnabled(data.registrationEnabled)
+    if (data) {
+      setRegistrationEnabled(data.registrationEnabled)
+      setPreferredAudioLanguages(data.preferredAudioLanguages)
+    }
   }, [data])
 
   const save = useMutation({
-    mutationFn: () => updateSiteSettings({ registrationEnabled }),
+    mutationFn: () => updateSiteSettings({ registrationEnabled, preferredAudioLanguages }),
     onSuccess: () => {
       toast.success(t('settings.saved'))
       void queryClient.invalidateQueries({ queryKey: ['admin', 'settings'] })
@@ -50,6 +55,24 @@ export function SettingsPanel() {
             />
             {t('admin.settings.registrationLabel')}
           </label>
+
+          <div className="flex flex-col gap-1.5">
+            <label className="text-sm font-medium" htmlFor="preferred-audio">
+              {t('admin.settings.preferredAudio')}
+            </label>
+            <Input
+              id="preferred-audio"
+              className="max-w-xs"
+              placeholder="rus, eng"
+              value={preferredAudioLanguages}
+              disabled={isLoading}
+              onChange={(e) => setPreferredAudioLanguages(e.target.value)}
+            />
+            <p className="text-xs text-muted-foreground">
+              {t('admin.settings.preferredAudioHint')}
+            </p>
+          </div>
+
           <div>
             <Button size="sm" disabled={isLoading || save.isPending} onClick={() => save.mutate()}>
               {t('common.save')}