feat: erweitere gap_fill-Übungen, um mehrere Wörter in Referenzen zu unterstützen

frontend/src/views/social/VocabLessonView.vue

@@ -2822,14 +2822,30 @@ export default {
           if (this.lesson && Array.isArray(this.lesson.chapterLexemeTraining) && this.lesson.chapterLexemeTraining.length) {
             const temps = this.lesson.chapterLexemeTraining.map((item, idx) => {
               const id = `cht-${this.lesson.id}-${String(item.id)}`;
+              // Wenn reference mehrere Wörter enthält, ersetze das erste Wort durch die Lücke
+              const ref = String(item.reference || '').trim();
+              let qText = `{gap} (${item.learning})`;
+              let answers = [ref];
+              if (ref) {
+                const parts = ref.split(/\s+/).filter(Boolean);
+                if (parts.length > 1) {
+                  const tail = parts.slice(1).join(' ');
+                  qText = `{gap} ${tail}`;
+                  answers = [parts[0]];
+                } else {
+                  // single token reference: show blank plus learning hint
+                  qText = `{gap} (${item.learning})`;
+                  answers = [parts[0]];
+                }
+              }
               return {
                 id,
                 lessonId: this.lesson.id,
                 exerciseTypeId: 1,
                 title: `Kapitel-Vokabel: ${item.learning}`,
                 instruction: this.$t('socialnetwork.vocab.courses.fillTheBlank') || 'Lückentext',
-                questionData: { type: 'gap_fill', text: `{gap} (${item.learning})` },
-                answerData: { type: 'gap_fill', answers: [item.reference] }
+                questionData: { type: 'gap_fill', text: qText },
+                answerData: { type: 'gap_fill', answers }
               };
             });
             this.lesson.grammarExercises = Array.isArray(this.lesson.grammarExercises)