Updates Tackle fields and draft cloudData (synced to Google Cloud
Marketplace when applicable).

Published offers (non-terminal): only
privateOffer.cloudData.acceptDeadlineTime may change. Use this to
extend the buyer accept-by date. Send no other cloudData keys, no
eula, no sow, and no top-level offerExpirationAt. GCP-hosted
documents are immutable after publish; eula/sow (including
documentUrns) cannot be changed. Read published custom EULA bytes with
GET …/documents and GET …/documents/{docId}. GCP caps accept-deadline
extensions at three months from publish time.

Draft offers: any cloudData fields allowed by GCP while in DRAFT.

Terminal offers (accepted, canceled, expired): marketplace fields are
locked; Tackle fields (metadata, users to notify, crmMetadata) still
update.

Example: extend the accept deadline on a published offer.

{
  "vendorId": "YOUR_VENDOR_ID",
  "privateOffer": {
    "cloudData": {
      "acceptDeadlineTime": "2030-06-15T00:00:00Z"
    }
  }
}