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/components/widgets/ListWidget.vue

@@ -30,21 +30,32 @@ export default {
     fallbackText() {
       if (this.data == null) return '';
       if (Array.isArray(this.data)) {
-        return this.data.length === 0 ? 'Keine Einträge' : `(${this.data.length} Einträge)`;
+        return this.data.length === 0
+          ? this.$t('widgets.list.noEntries')
+          : this.$t('widgets.list.entriesCount', { count: this.data.length });
       }
       if (typeof this.data === 'object') {
         const keys = Object.keys(this.data);
-        return keys.length === 0 ? '—' : `(${keys.length} Felder)`;
+        return keys.length === 0 ? '—' : this.$t('widgets.list.fieldsCount', { count: keys.length });
       }
       return String(this.data);
     }
   },
   methods: {
+    getDateLocale() {
+      const locale = this.$i18n?.locale;
+      return {
+        de: 'de-DE',
+        en: 'en-GB',
+        es: 'es-ES',
+        ceb: 'fil-PH'
+      }[locale] || 'de-DE';
+    },
     formatDatum(dateStr) {
       if (!dateStr) return '';
       const d = new Date(dateStr);
       if (Number.isNaN(d.getTime())) return String(dateStr);
-      return d.toLocaleDateString('de-DE', {
+      return d.toLocaleDateString(this.getDateLocale(), {
         weekday: 'short',
         day: 'numeric',
         month: 'short',