Updates an existing transaction. The request body must include client_id plus
any form fields to update. Use GET /api/v3/transaction?client_id=X to retrieve
the current field values and form definition before submitting. Not available
for vendor market teams.
Deprecated: use PATCH /api/v3/transactions/{client_id} instead. This URL remains functional but will be removed in a future release.

When team_form_id is -4 (status drawer), only the fields present in the request
body are written back — absent fields are not cleared. Setting signed_dt on a
seller transaction automatically clears listing_dt unless listing_dt is also
included in the same request.