The MediaWiki donor export job currently writes its output CSV (optionally encrypted) to a local path and stops there. We need it to optionally SFTP the file to a configured remote host after export, so the MediaWiki side can pick it up automatically without manual file transfer.
- Add SFTP configuration options (host, port, username, key path, remote path) to the job's YAML config
- After writing (and optionally encrypting) the CSV, upload it to the configured SFTP target
- SFTP upload should be optional - if no SFTP config is present, the job behaves as it does today