feat: implement comprehensive backup and restore system with S3 support

- Add S3/MinIO storage adapter with multipart upload support
- Implement database backup service for SQLite and PostgreSQL
- Create backup manifest generator for tracking backup contents
- Enhance backup service with S3 integration and incremental backups
- Add restore service with safety measures and rollback capability
- Create comprehensive test suite for all backup functionality
- Add admin API endpoints for backup/restore management
- Implement frontend UI with dashboard, configuration, and restore wizard
- Add roadmap section to README with implemented backup feature

This implementation provides:
- Multiple backup destinations (local, rsync, S3/MinIO)
- Intelligent change detection to minimize backup frequency
- Full database backups with compression
- Manifest-based restore with integrity validation
- Pre-restore safety backups with rollback
- Comprehensive error handling and monitoring
- User-friendly admin interface

🤖 Generated with Claude Code

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

frontend/src/components/admin/index.ts

@@ -22,4 +22,8 @@ export { ThemeDisplay } from './ThemeDisplay';
 export { ThemeEditorModal } from './ThemeEditorModal';
 export { HeroPhotoSelector } from './HeroPhotoSelector';
 export { PhotoUploadModal } from './PhotoUploadModal';
-export { GalleryPreview } from './GalleryPreview';
+export { GalleryPreview } from './GalleryPreview';
+export { BackupDashboard } from './BackupDashboard';
+export { BackupConfiguration } from './BackupConfiguration';
+export { BackupHistory } from './BackupHistory';
+export { RestoreWizard } from './RestoreWizard';