Create a new practitioner for the tenant

Creates a new practitioner record scoped to the requesting tenant. Use this when onboarding a new provider who does not yet exist in the system; if the practitioner already exists for this tenant, the server returns 409 — use PUT /practitioners/{id} to update an existing record instead. The request body accepts three payload shapes: a wrapped object with a top-level data field, a direct practitioner object, or an extended form that also includes groups and networks for simultaneous association; the payload is validated against the practitioner JSON schema before persistence. Creating a practitioner here does not itself trigger a downstream credentialing workflow.