- Add cista/util/diskspace.py with MIN_FREE_BYTES limit and cached
check_free_space() helper.
- Check available space in File.write() before ftruncate/write.
- Catch ENOSPC in File.write and re-raise as InsufficientStorageError.
- upload_file_chunk catches both proactive and ENOSPC errors and
returns HTTP 507 Insufficient Storage.
- Add tests for low-disk rejection and ENOSPC handling.
Increases block size to 16 MiB and adjusts progress display to work smoothly with that. Also removes download WS that was already unused. Provides faster upload speed than over WS.
LeoVasanko