Implement watchers for courseId and lessonId in VocabLessonView to reset flags on changes

- Added watchers for courseId and lessonId to reset flags related to lesson completion and navigation when either value changes, ensuring proper lesson loading and state management.
- Removed redundant method definitions for courseId and lessonId, streamlining the component's code structure and improving maintainability.

frontend/src/views/social/VocabLessonView.vue

@@ -414,6 +414,24 @@ export default {
       }
     }
   },
+  watch: {
+    courseId(newVal, oldVal) {
+      if (newVal !== oldVal) {
+        // Reset Flags beim Kurswechsel
+        this.isCheckingLessonCompletion = false;
+        this.isNavigatingToNext = false;
+        this.loadLesson();
+      }
+    },
+    lessonId(newVal, oldVal) {
+      if (newVal !== oldVal) {
+        // Reset Flags beim Lektionswechsel
+        this.isCheckingLessonCompletion = false;
+        this.isNavigatingToNext = false;
+        this.loadLesson();
+      }
+    }
+  },
   methods: {
     _extractVocabFromExercises(exercises) {
       // Sicherstellen, dass exercises ein Array ist
@@ -530,24 +548,6 @@ export default {
       console.log(`[_extractVocabFromExercises] Ergebnis:`, result.length, 'Vokabeln');
       return result;
     },
-    courseId(newVal, oldVal) {
-      if (newVal !== oldVal) {
-        // Reset Flags beim Kurswechsel
-        this.isCheckingLessonCompletion = false;
-        this.isNavigatingToNext = false;
-        this.loadLesson();
-      }
-    },
-    lessonId(newVal, oldVal) {
-      if (newVal !== oldVal) {
-        // Reset Flags beim Lektionswechsel
-        this.isCheckingLessonCompletion = false;
-        this.isNavigatingToNext = false;
-        this.loadLesson();
-      }
-    }
-  },
-  methods: {
     async loadLesson() {
       // Verhindere mehrfaches Laden
       if (this.loading) {