Overview
Vendor profile endpoints.
Duplicate handling
A create request is matched against existing vendors in the workspace by display name, or by email when one is supplied. Use dedupe_mode on the request body to choose what happens when a match is found:
The 409 body carries the vendor that was matched, so you can link to it or retry the request with dedupe_mode set to add.
Default payment term
Set payment_term_id on a vendor to give it a default payment term from /configs/payment-terms. New bills for that vendor use it whenever the request names neither a payment_term_id nor a due_date.
On update, send payment_term_id to change the default, or clear_payment_term set to true to remove it. A term that is not active, or does not exist in the workspace, is rejected with 404.
Read the default from the vendor endpoints. A vendor embedded in another document is a summary and may not carry it.

