Add homework review workflow: statuses, audio, file attachments, tabs

- HomeworkSubmission: add status (PENDING/REVIEWING/APPROVED/REJECTED) + statusAt
- HomeworkFeedback: add files (Json) + audioUrl fields
- Curator detail page: meta table, content tabs, feedback history with audio/files
- FeedbackForm: file upload, audio recorder (Web Audio API + S3), action buttons
- AudioRecorder component: record → preview → upload to S3
- ContentTabs: toggle between homework description and lesson content (TipTap read-only)
- Homework list: 4-color status badges with proper filtering
- API routes: /api/curator/upload and /api/curator/audio-upload

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/admin/homework-filters.tsx

@@ -64,8 +64,10 @@ export function HomeworkFilters({ courses }: { courses: Course[] }) {
         onBlur={(e) => (e.currentTarget.style.borderColor = "var(--border)")}
       >
         <option value="">Все статусы</option>
-        <option value="pending">Ожидают проверки</option>
-        <option value="reviewed">Проверено</option>
+        <option value="pending">Новые</option>
+        <option value="reviewing">На рассмотрении</option>
+        <option value="approved">Одобрено</option>
+        <option value="rejected">Отклонено</option>
       </select>
 
       {/* Course */}