create_upload_url
Preferred way to host a file. Reserves a link and returns a short-lived upload_url on filetourl.org itself, safe for AI agent sandboxes that only allow egress to trusted domains, since the upload never has to leave filetourl.org. Send the raw file bytes yourself with a single HTTP PUT to that URL (do not read the file into this conversation, and do not base64-encode it). The public_url returned works as soon as the PUT succeeds. Needs a FileToUrl Developer API key.
file_name必填content_type