The commit refactors the chunked upload system to support a transformation pipeline. Key changes include:
- Replace SSE field names for consistency (sseChannelId, sseUrl)
- Fix progress reporting structure with state and percent fields
- Add transformation handlers (a-dash, mq-hls, img-compress, video-compress)
- Create new Upload class with clear separation of concerns
- Improve file processing workflow with better directory structure
- Fix typo in UploadButton component (progess → progress)
- Remove deprecated file processing services
