Function parse_data_dir 

pub fn parse_data_dir(input: &str) -> Result<Url>

Parse a CLI / env --data-dir argument into a Url. Delegates to Lance’s own uri_to_url, which handles every form pond cares about:

• bare paths like /srv/pond -> file:///srv/pond
• explicit file://... URIs
• object-store URIs (s3://, gs://, az://, …)
• tilde expansion (~/...)
• Windows drive letters (we don’t ship Windows, but the parser handles it)

Using Lance’s parser keeps pond’s CLI parse path identical to what Lance uses internally - no risk of pond accepting a string Lance later rejects.