Creates a new client (individual or legal entity) in the authenticated company's registry. A client created through this endpoint is an independent record — it is not automatically linked to any card — and becomes part of the company's general client registry, available to be referenced later in any credit process.The request body only requires companyId and taxId (CPF or CNPJ, digits only). The fields property is optional and carries values for the company's dynamic client fields (the same set of fields configurable through the Client Configuration domain) — each array position represents one filled-in field.The ag-flow-id header is optional on these calls; when provided, it identifies an existing company flow (available from GET /v1/flows, Flow domain, or from the flow's URL in the AgFlow application) — omitting it does not block the call.