Register Deal Document

A single document on a deal.

id is the underlying document id (stable across folder moves) — the same id the download route accepts. size_bytes may be null for older rows whose size was never persisted. vault tags which of the deal's vaults the document lives in (a document copied into more than one vault appears once per vault). Uploader attribution and document classification are deliberately omitted from Slice 1 (the listing query does not load those relationships; see the blueprint module docstring).