Add feedback system functionality

- Implement feedback management system in admin interface
- Add feedback processing and AI-based features
- Update user interface with new feedback components
- Modify server-side API endpoints for feedback handling
- Enhance worker.js for background feedback processing
- Update deployment configuration for feedback components

Co-authored-by: openhands <openhands@all-hands.dev>

public/admin.js

@@ -51,6 +51,7 @@ function buildSidebar(active) {
     { page: 'dashboard', label: 'Дашборд', icon: 'layout-dashboard' },
     { page: 'journal', label: 'Журнал', icon: 'book-open' },
     { page: 'lessons', label: 'Отчёты о занятиях', icon: 'notebook-pen' },
+    { page: 'feedback', label: 'Обратная связь', icon: 'message-square-heart' },
     { page: 'notifications', label: 'Уведомления', icon: 'bell', badge: true },
     { page: 'chat', label: 'Чаты', icon: 'messages-square', chatBadge: true },
     { page: 'students', label: 'Ученики', icon: 'graduation-cap' },