feat(vocab): add course language name handling in VocabLessonView

- Introduced new properties for course language names to enhance clarity in vocabulary preparation.
- Implemented a method to load course language names from the API, improving localization and user experience.
- Updated label logic to utilize course-specific language names, ensuring accurate representation in vocabulary lessons.

frontend/src/views/social/VocabLessonView.vue

@@ -1012,6 +1012,8 @@ export default {
       exerciseSequentialIndex: 0,
       /** Aus vorherigen Lektionen (MC-Optionen nach Fragentyp Ziel-/Muttersprache) */
       distractorPool: { target: [], native: [] },
+      courseLanguageName: '',
+      courseNativeLanguageName: '',
       /** Fortschritt aller Kurslektionen inkl. lessonState für Spezial-Trainer-Boost */
       courseProgressList: [],
       /** { [exerciseId]: { options: string[], useTextAnswer: boolean } } */
@@ -1297,14 +1299,16 @@ export default {
     },
     prepTargetLabel() {
       return String(
-        this.lesson?.course?.languageName
+        this.courseLanguageName
+        || this.lesson?.course?.languageName
         || this.lesson?.languageName
         || this.$t('socialnetwork.vocab.courses.vocabPrepTargetLabel')
       ).toUpperCase();
     },
     prepGlossLabel() {
       return String(
-        this.lesson?.course?.nativeLanguageName
+        this.courseNativeLanguageName
+        || this.lesson?.course?.nativeLanguageName
         || this.lesson?.nativeLanguageName
         || this.$t('socialnetwork.vocab.courses.vocabPrepGlossLabel')
       ).toUpperCase();
@@ -2133,6 +2137,8 @@ export default {
       this.vocabTrainerCurrentAttempts = 0;
       this.vocabTrainerReviewAttempts = 0;
       this.courseProgressList = [];
+      this.courseLanguageName = '';
+      this.courseNativeLanguageName = '';
       this.distractorPool = { target: [], native: [] };
       this.mcRandomizedOptions = {};
       // Reset Flags
@@ -2154,6 +2160,7 @@ export default {
       try {
         const res = await apiClient.get(`/api/vocab/lessons/${this.lessonId}`);
         this.lesson = res.data;
+        await this.loadCourseLanguageNames();
         await this.loadCourseProgressForBoost();
         debugLog('[VocabLessonView] Geladene Lektion:', this.lesson?.id, this.lesson?.title);
         if (this.$route.query.assistant) {
@@ -2199,6 +2206,16 @@ export default {
         this.courseProgressList = [];
       }
     },
+    async loadCourseLanguageNames() {
+      try {
+        const { data } = await apiClient.get(`/api/vocab/courses/${this.courseId}`);
+        this.courseLanguageName = String(data?.languageName || '').trim();
+        this.courseNativeLanguageName = String(data?.nativeLanguageName || '').trim();
+      } catch (e) {
+        this.courseLanguageName = '';
+        this.courseNativeLanguageName = '';
+      }
+    },
     focusAssistantCard() {
       const target = this.$refs.assistantCard;
       if (!target || typeof target.scrollIntoView !== 'function') {