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/DiaryView.vue

@@ -2,15 +2,15 @@
     <div class="diary-view">
         <section class="diary-hero surface-card">
             <div>
-                <span class="diary-kicker">Persönliche Einträge</span>
+                <span class="diary-kicker">{{ $t('socialnetwork.diary.kicker') }}</span>
                 <h2>{{ $t('socialnetwork.diary.title') }}</h2>
-                <p>Gedanken, Notizen und kurze Updates in einer ruhigen, persönlichen Ansicht.</p>
+                <p>{{ $t('socialnetwork.diary.intro') }}</p>
             </div>
         </section>
 
         <section class="new-entry-section surface-card">
             <h3>{{ isEditing ? $t('socialnetwork.diary.editEntry') : $t('socialnetwork.diary.newEntry') }}</h3>
-            <textarea v-model="newEntryText" placeholder="Write your diary entry..."></textarea>
+            <textarea v-model="newEntryText" :placeholder="$t('socialnetwork.diary.placeholder')"></textarea>
             <div class="form-actions">
                 <button @click="saveEntry">{{ isEditing ? $t('socialnetwork.diary.update') : $t('socialnetwork.diary.save')
                     }}</button>