Create a caller identity share link

Creates a single-use link (valid 7 days) where the end business fills in the caller identity itself, with no Zernio login: display name, logo, call reasons, the authorizer and the three references. What it submits lands under your team as requested, the same review as an API submission, and branded_calling.identity.status_updated fires. Scope the link with identityId (complete an identity that is requested or changes_requested), with enterpriseId (a new identity for a registered business), or with neither (the business registers itself and its first identity). The person opening the link can forward a fresh one to someone else, which retires theirs.