Uploading with up!link

Use curl only. Never print or commit UPLINK_API_KEY. If UPLINK_API_KEY is missing, ask the user to configure it rather than guessing.

Keys shaped uplink_<host>_<secret> embed the server address. Derive the base URL first:

rest="${UPLINK_API_KEY#uplink_}"
base="${UPLINK_BASE_URL:-https://${rest%_*}}"

If the key lacks the uplink_ prefix, UPLINK_BASE_URL is required instead; ask the user for it when unset.

Upload a local file, defaulting to a temporary link: