Generates a PDF representation of the current page.
Returns a Download object which can contain a URL to the PDF or its Base64 encoded data.
Example: pdf(options: { format: A4, landscape: true, printBackground: true })
DownloadRepresents a downloadable resource, typically a file generated by an action (e.g., PDF or screenshot).
It may contain a URL to the resource or the resource data directly encoded as a Base64 string.