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/ForumTopicView.vue

@@ -4,7 +4,7 @@
             <div>
                 <div class="forum-topic-back link" @click="openForum()">{{ $t('socialnetwork.forum.title') }} {{ forumName }}</div>
                 <h2 v-if="forumTopic">{{ forumTopic }}</h2>
-                <p>Diskussionen, Antworten und neue Beiträge in einer fokussierten Lesefläche.</p>
+                <p>{{ $t('socialnetwork.forum.topicIntro') }}</p>
             </div>
         </section>