feat(vocab): implement SRS features and enhance vocabulary management

- Added new endpoints in vocabController for retrieving SRS due items and reviewing SRS items, improving spaced repetition support.
- Updated vocabService to handle SRS item creation and scheduling, ensuring effective tracking of vocabulary exposure.
- Enhanced vocabRouter with new routes for SRS functionalities, facilitating user interaction with spaced repetition features.
- Modified VocabPracticeDialog and VocabCourseView to integrate SRS due items, providing users with timely review opportunities.
- Updated translations and UI elements to reflect new SRS features, enhancing user experience and accessibility.

frontend/src/views/social/VocabCourseView.vue

@@ -49,11 +49,23 @@
             <p>{{ $t('socialnetwork.vocab.courses.courseFlowIntro') }}</p>
           </div>
           <div class="course-flow__stats">
+            <span class="course-flow__stat">{{ $t('socialnetwork.vocab.courses.srsDueStat', { count: srsDueCount }) }}</span>
             <span class="course-flow__stat">{{ $t('socialnetwork.vocab.courses.courseFlowReviewStat', { count: dueReviewLessons.length }) }}</span>
             <span class="course-flow__stat">{{ $t('socialnetwork.vocab.courses.courseFlowBlockStat', { block: currentBlockNumber || '—' }) }}</span>
           </div>
         </div>
 
+        <div v-if="srsDueCount > 0" class="course-srs-plan">
+          <div>
+            <span class="course-srs-plan__eyebrow">{{ $t('socialnetwork.vocab.courses.srsEyebrow') }}</span>
+            <h4>{{ $t('socialnetwork.vocab.courses.srsTitle', { count: srsDueCount }) }}</h4>
+            <p>{{ $t('socialnetwork.vocab.courses.srsIntro') }}</p>
+          </div>
+          <button type="button" class="course-today-plan__action" :disabled="srsLoading" @click="openSrsPractice">
+            {{ srsLoading ? $t('general.loading') : $t('socialnetwork.vocab.courses.srsStart') }}
+          </button>
+        </div>
+
         <div v-if="todayRecommendedSteps.length > 0" class="course-today-plan">
           <h4 class="course-today-plan__title">{{ $t('socialnetwork.vocab.courses.courseTodayPlanTitle') }}</h4>
           <p class="course-today-plan__intro">
@@ -325,6 +337,8 @@ export default {
       course: null,
       progress: [],
       chapters: [],
+      srsDueItems: [],
+      srsLoading: false,
       showAddLessonDialog: false,
       assistantSettings: null,
       lessonFormTouched: false,
@@ -366,6 +380,9 @@ export default {
     currentBlockNumber() {
       return this.currentLesson?.pedagogy?.blockNumber || null;
     },
+    srsDueCount() {
+      return Array.isArray(this.srsDueItems) ? this.srsDueItems.length : 0;
+    },
     dueReviewLessons() {
       return this.sortedLessons
         .filter((lesson) => {
@@ -504,6 +521,7 @@ export default {
         const res = await apiClient.get(`/api/vocab/courses/${this.courseId}`);
         this.course = res.data;
         await this.loadProgress();
+        await this.loadSrsDueItems();
         if (this.course.languageId) {
           await this.loadChapters();
         }
@@ -522,6 +540,20 @@ export default {
         this.progress = [];
       }
     },
+    async loadSrsDueItems() {
+      this.srsLoading = true;
+      try {
+        const { data } = await apiClient.get(`/api/vocab/courses/${this.courseId}/srs/due`, {
+          params: { limit: 40 }
+        });
+        this.srsDueItems = Array.isArray(data?.items) ? data.items : [];
+      } catch (e) {
+        console.warn('Konnte SRS-Fälligkeiten nicht laden:', e);
+        this.srsDueItems = [];
+      } finally {
+        this.srsLoading = false;
+      }
+    },
     async loadChapters() {
       try {
         const res = await apiClient.get(`/api/vocab/languages/${this.course.languageId}/chapters`);
@@ -814,6 +846,17 @@ export default {
         lessonId: lesson.id
       });
     },
+    openSrsPractice() {
+      if (!this.srsDueItems.length) {
+        return;
+      }
+      this.$refs.practiceDialog?.open?.({
+        courseId: this.courseId,
+        initialPool: this.srsDueItems,
+        srsMode: true,
+        onClose: () => this.loadSrsDueItems()
+      });
+    },
     openLessonReview(lessonId) {
       this.$router.push(`/socialnetwork/vocab/courses/${this.courseId}/lessons/${lessonId}/review`);
     },
@@ -1010,6 +1053,40 @@ export default {
   gap: 14px;
 }
 
+.course-srs-plan {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 16px;
+  margin-bottom: 20px;
+  padding: 16px 18px;
+  border-radius: 14px;
+  border: 1px solid rgba(102, 153, 126, 0.38);
+  background: linear-gradient(135deg, rgba(232, 247, 238, 0.95), rgba(255, 251, 240, 0.8));
+}
+
+.course-srs-plan__eyebrow {
+  display: inline-flex;
+  margin-bottom: 4px;
+  font-size: 0.72rem;
+  font-weight: 800;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  color: #4f7b60;
+}
+
+.course-srs-plan h4,
+.course-srs-plan p {
+  margin: 0;
+}
+
+.course-srs-plan p {
+  margin-top: 6px;
+  color: var(--color-text-secondary, #5c534c);
+  font-size: 0.88rem;
+  line-height: 1.45;
+}
+
 .course-flow-card {
   padding: 16px;
   border: 1px solid var(--color-border);

frontend/src/views/social/VocabLessonView.vue

@@ -3602,6 +3602,23 @@ export default {
     normalizeVocab(s) {
       return this.normalizeComparableText(s);
     },
+    reportSrsReviewForCurrentQuestion(isCorrect) {
+      if (!this.currentVocabQuestion?.vocab || !this.courseId) {
+        return;
+      }
+      const vocab = this.currentVocabQuestion.vocab;
+      apiClient.post('/api/vocab/srs/review', {
+        courseId: this.courseId,
+        lessonId: vocab.lessonId || this.lessonId,
+        itemKey: vocab.itemKey || null,
+        learning: vocab.learning,
+        reference: vocab.reference,
+        direction: this.vocabTrainerDirection,
+        correct: Boolean(isCorrect)
+      }).catch((error) => {
+        console.warn('[VocabLessonView] SRS review could not be saved:', error);
+      });
+    },
     checkVocabAnswer() {
       if (!this.currentVocabQuestion) return;
       
@@ -3638,6 +3655,7 @@ export default {
         stats.wrong++;
         this.queueFailedVocab(this.currentVocabQuestion.vocab);
       }
+      this.reportSrsReviewForCurrentQuestion(this.vocabTrainerLastCorrect);
       
       this.vocabTrainerAnswered = true;