8FF - Funnel Event Producer | 🎯 Webhook → Kafka

## 8FF Funnel Event Producer

**Trigger:** POST `/webhook/8ff-funnel-track`

**Flow:**
1. Receive event from Vercel `/api/track` Edge
2. Validate event-type ∈ ALLOWED_EVENTS
3. Enrich (ts, ua, ip, source)
4. Produce to Kafka topic `8ff.funnel.events` (key=session_id for partition-stickiness)
5. Respond 200 OK to caller

**Cred:** `8FF Kafka Tower` (kafkaTower8FF01)

**Downstream-Consumers:**
- 8ff-retargeting-trigger (filters drop_off_at_*)
- 8ff-conversion-loop-closer (filters conversion)
- 8ff-analytics-aggregator (all events)

**Stack:** Producer-Layer of Closed-Loop-Funnel-System (Vault-Doc 2026-05-05)