feat(localization): expand language support and enhance UI for user settings

- Added support for additional UI locales including Cebuano and Spanish, improving accessibility for a broader user base.
- Updated language selection components in the AppHeader and SettingsWidget to reflect new language options, enhancing user experience.
- Enhanced localization of various UI elements across components, ensuring consistent language representation and improved user engagement.
- Implemented logic to synchronize user language preferences with backend settings, providing a seamless experience when changing languages.

frontend/src/views/social/VocabSubscribeView.vue

@@ -1,7 +1,7 @@
 <template>
   <div class="vocab-subscribe-view">
     <section class="vocab-subscribe-hero surface-card">
-      <span class="vocab-subscribe-hero__eyebrow">Vokabeltrainer</span>
+      <span class="vocab-subscribe-hero__eyebrow">{{ $t('socialnetwork.vocab.subscribeHeroEyebrow') }}</span>
       <h2>{{ $t('socialnetwork.vocab.subscribeTitle') }}</h2>
       <p>{{ $t('socialnetwork.vocab.subscribeHint') }}</p>
     </section>