Create or update the link between a referrer and a referrer organization.
The link is identified by the organization id, so there is no separate link
identifier to track.

Returns 201 when the link is created and 200 when it already existed.
Every property on the request body is optional and behaves three ways: an
omitted property leaves the stored value unchanged, null clears it, and a
value replaces it. When the link is created, properties you omit are left
unset and status defaults to ACTIVE. status is case-insensitive. A
request that changes nothing performs no write, so updatedAt does not move.

Returns 400 when status is not a recognized value, when association.id
does not resolve to a referrerOrgAssociation attribute, or when address
carries invalid or partial coordinates.

Requires the referrers scope. The referrer must be within the API key's
permitted locations; the organization and the association attribute are each
resolved by id alone, with no location restriction.