Expose message lineage (metadata.source) on inbox message reads

Hi! We run WhatsApp bots on top of your inbox API and we need to tell apart who authored an outgoing message when re-reading a conversation: our bot (API), a human agent replying from the Zernio dashboard, or a broadcast/template.

You already track this internally: GET /v1/analytics/inbox/source-breakdown reports the lineage metadata.source set at ingest time (human / api / broadcast / workflow / ...), and our tests confirm dashboard replies are counted as human. However, GET /v1/inbox/conversations/{id}/messages returns those same messages with no metadata.source at all (only whatsapp_business_app / coexistence_history are exposed today), so API-sent and dashboard-sent messages are indistinguishable on read.

Request: serialize the existing lineage value in the message objects returned by the messages GET (and ideally in message.sent / message.received webhook payloads). No new tracking needed, just exposing the field you already store. Our use case: when a human agent replies from the dashboard, our bot should automatically go quiet in that thread instead of talking over them, the same way we already do with whatsapp_business_app messages on coexistence numbers.