Add users to audience

Upload user data to a customer_list audience. Data is SHA256-hashed server-side before sending to the platform. Email is used on every platform; phone is used on Meta only (other platforms ignore it). On TikTok and Pinterest, the first upload also provisions the audience (deferred create). LinkedIn uploads are full-replace. Max 10,000 users per request.

customer_list only. A LinkedIn company_list audience takes company rows, not people: send those to POST /v1/ads/audiences/{audienceId}/companies. This endpoint 422s for every other audience type.