Changes to PUT /clinic-config/document-layout — replaces the PDF layout (ITE-1334). Every field is written, so a later default change never silently flips a clinic's saved choice.

added the new optional request property letterhead (media type: application/json)

added the new optional request property letterhead (media type: text/json)

added the new optional request property letterhead (media type: application/*+json)

added the optional property letterhead to the response with the 200 status (media type: text/plain)

added the optional property letterhead to the response with the 200 status (media type: application/json)

added the optional property letterhead to the response with the 200 status (media type: text/json)

endpoint added