Features:
- Real-time upload progress tracking with AJAX polling and session-based monitoring
- API endpoint /api/upload_progress/<session_id> for progress updates
- Video conversion progress tracking with background threads
- Mobile-responsive design for manage_group page
- Player status cards with feedback, playlist sync, and last activity
- Bootstrap Icons integration throughout UI
- Responsive layout (1/4 group info, 3/4 players on desktop)
- Video thumbnails with play icon, image thumbnails in media lists
- Bulk selection and delete for group media
- Enhanced logging for video conversion debugging
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