feat(vocab): add dashboard learning summary and related endpoints

- Introduced `getDashboardLearningSummary` method in `VocabService` to provide a compact overview of enrolled courses and current lessons for users.
- Updated `vocabController` to include a new route for the dashboard widget, allowing users to access their learning summary.
- Enhanced `vocabRouter` to route requests for the new dashboard widget endpoint.
- Added localization support for the new dashboard features across multiple languages, improving user engagement and accessibility.
- Updated UI components to integrate the new dashboard widget, ensuring a seamless user experience.

frontend/src/components/DashboardWidget.vue

@@ -28,10 +28,12 @@ import ListWidget from './widgets/ListWidget.vue';
 import BirthdayWidget from './widgets/BirthdayWidget.vue';
 import UpcomingEventsWidget from './widgets/UpcomingEventsWidget.vue';
 import MiniCalendarWidget from './widgets/MiniCalendarWidget.vue';
+import VocabCoursesWidget from './widgets/VocabCoursesWidget.vue';
 
 function getWidgetComponent(endpoint) {
   if (!endpoint || typeof endpoint !== 'string') return ListWidget;
   const ep = endpoint.toLowerCase();
+  if (ep.includes('vocab/dashboard-widget')) return VocabCoursesWidget;
   if (ep.includes('falukant')) return FalukantWidget;
   if (ep.includes('news')) return NewsWidget;
   if (ep.includes('calendar/widget/birthdays')) return BirthdayWidget;
@@ -42,7 +44,7 @@ function getWidgetComponent(endpoint) {
 
 export default {
   name: 'DashboardWidget',
-  components: { FalukantWidget, NewsWidget, ListWidget, BirthdayWidget, UpcomingEventsWidget, MiniCalendarWidget },
+  components: { FalukantWidget, NewsWidget, ListWidget, BirthdayWidget, UpcomingEventsWidget, MiniCalendarWidget, VocabCoursesWidget },
   props: {
     widgetId: { type: String, required: true },
     title: { type: String, required: true },