* Clarified the description of the `--ref` flag to specify its purpose more accurately.
* Ensures users understand that it narrows down deletion by cache key and ref.
* Implemented test cases for handling the `--ref` flag in cache deletion commands.
* Added validation for using `--ref` with cache key and ID.
* Ensured proper error messages are returned for invalid usage of `--ref`.
- Introduced `--ref` flag to narrow down cache deletion to a specific branch or PR reference.
- Updated command examples to include usage of `--ref`.
- Added validation to ensure `--ref` cannot be used with `--all` and must accompany a cache key/ID.
