Refactor i18n integration in superuser navigation menu items

- Replaced `useI18n` with global `i18n` instance for consistency.
- Adjusted translation function to `i18n.global.t` for improved maintainability.

src/components/models/navigation/items/NavigationMenuItemsSuperUser.vue

@@ -2,11 +2,11 @@
 import { NavigationItemProps } from "@/components/models/navigation/NavigationItem.vue";
 import {computed, defineComponent} from 'vue';
 import SessionUser from "@/components/session/token/SessionUser.vue";
-import { useI18n } from 'vue-i18n';
+import i18n from '@/i18n';
 
 const firstToUpperCase = (str: string) => str.charAt(0).toUpperCase() + str.slice(1);
 
-const { t } = useI18n();
+const t = (key: string) => i18n.global.t(key);
 
 const items = computed<NavigationItemProps[]>(() => [
   // Invoicing