first release

Optimize: Non-blocking uploads with cancellation support

- Use compute() isolates for compression/decompression
- Use compute() for chunk splitting/merging
- Add CancelToken support to cancel uploads/downloads
- Add cancel button in progress bar UI
- Show current operation name during transfer
- Add 500ms delay between chunks to avoid rate limits
- Reduce timeouts for faster failure detection

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>