Attach a pre-parsed document to a thread and fire the post-document workflow.

Mirrors the Healthie webhook path minus the download-and-parse step: the caller has already produced the plain-text content and bounds-flagged results, so we store the payload in thread.json_data["documents"] and trigger ReceivedHealthieWebhookTrigger. HealthieProcessWebhookDocument short-circuits on PreParsedDocument; every other action in the Longevity trigger step list runs unchanged.

Upsert semantics on healthie_document_id: a re-send for the same document replaces the stored entry in place and re-fires the trigger, so downstream state stays in sync with whatever the Longevity dashboard produced most recently.