Deal lifecycle

Sovrn owns the deal's status; you observe it through the read endpoints. A deal
with a future start date is created as scheduled and becomes active on its
start date. Sovrn operators may pause or archive a deal; those changes surface on
the next read of that deal.

Statuses

Status	Meaning
`active`	Live and eligible to transact.
`scheduled`	Created with a future start date; becomes `active` on that date.
`paused`	Temporarily paused by a Sovrn operator.
`review`	Pending operator review.
`dsp review`	Awaiting DSP confirmation (applies to certain buyers).
`archived`	Terminated; no longer active.

📘
Judging freshness
GET /deal-requests/{id} refreshes the status from source (cached ~30s) and
reports statusAsOf. If that refresh fails, it returns the last-known status
with a 200 (not an error) — always read statusAsOf to judge freshness. The
list endpoint does not refresh; poll the by-id endpoint for current status.