Authenticate with an Organization Admin User API key, sent in the
skyfire-api-key header. Keys belonging to callers whose organization role is
ADMIN are accepted; a MEMBER key, or any Agent API
key, is rejected with 401.

The new user is always created in your organization. It is derived from
the API key, and there is no orgId field in the request body.

The role you assign

What this call creates

A single request creates:

1. The organization user.
2. A buyer agent named Buyer 1, with a wallet.
3. An API key for that buyer agent, returned as buyerAgent.apiKey.
4. If role is ADMIN, an Organization Admin User API key, returned as
   userApiKey.

If any step fails, the whole transaction is rolled back and no user is created.

buyerAgent.apiKey and userApiKey are returned only in this response

and cannot be retrieved again. Store them securely before discarding the
response.

For role: "MEMBER", userApiKey is omitted from the response body
entirely. It is not returned as null.