Record attributes, events and purchases (Braze)

Braze's /users/track, so an app sending to Braze can send here too while it moves, by pointing its REST endpoint at …/v1/compat/braze. Each item names its person by external_id (the contact's externalId) or email; a person not yet known is created. first_name, last_name, email, phone and country fill those fields; an email_subscribe or push_subscribe of unsubscribed withdraws that consent; every other key becomes an attribute. Consent is never granted here: import it with its evidence. A purchase is recorded as a Product Purchased event with product_id, currency, price, quantity and total. Items that fail are listed in errors; the rest apply. Agent keys are refused.

Requires API-key scope: contacts:write and events:write.