Mirrors Meta's POST /{pixelId}/events — server-side event delivery, the resilient counterpart to browser-side Pixel tracking (post-iOS14.5/ATT signal loss).

• Body: { data: [...events], test_event_code? }.
• Each event: event_name, event_time, action_source, user_data (hashed identifiers — em/ph SHA-256, or unhashed client_ip_address/client_user_agent/fbc/fbp per Meta's own spec), custom_data (value, currency).
• Find a pixel id via GET /accounts/{accountId}/adspixels.
• Write — needs a write-scoped token. Body may carry hashed customer PII — never logged.