Add profile routes to backend and frontend; implement user state handling for holidays and workdays, and update UI components for profile settings

frontend/src/App.vue

@@ -73,6 +73,7 @@ const pageTitle = computed(() => {
     'workdays': 'Arbeitstage',
     'calendar': 'Kalender',
     'admin-holidays': 'Feiertage',
+    'settings-profile': 'Persönliches',
     'entries': 'Einträge',
     'stats': 'Statistiken'
   }