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/i18n/locales/ceb/general.json

@@ -81,6 +81,16 @@
         },
         "falukant": {
             "emptyValue": "—"
+        },
+        "vocabCourses": {
+            "empty": "Wala ka pa nakasulod sa bisan unsang kurso sa bokabularyo.",
+            "browseCourses": "Tan-awa ang mga kurso",
+            "unnamedCourse": "Kurso nga walay titulo",
+            "lessonLine": "Leksyon #{number}: {title}",
+            "noLessons": "Walay mga leksyon niini nga kurso.",
+            "allDone": "Natapos na ang tanang leksyon",
+            "openLesson": "Adto sa leksyon",
+            "openCourse": "Ablihi ang kurso"
         }
     },
     "gender": {