Major improvements:
- Fix WebSocket connection loss issue by gracefully falling back to HTTP polling
- Add 5 independent video output ports (video1-video5) for multi-video support
- Optimize multi-video processing by skipping frame extraction (saves time)
- Add placeholder video generation for empty video outputs to prevent downstream errors
- Improve frame dimension normalization for mixed-resolution videos
Changes:
- WebSocket errors now downgrade to HTTP polling instead of failing immediately
- Support up to 5 videos with automatic placeholder generation for unused slots
- Single video: extracts frames normally
- Multiple videos: skips frame extraction, uses placeholder for video_frames output
- All video outputs now guaranteed to be valid VideoFromFile objects