Retrieves the Assembly's administrative contracts, including modality, contractor name and tax id (CPF/CNPJ), object, value, originating procurement process, and validity period.
Value
A tibble with one row per contract: modalidade,
numero_contrato, ano, contratada, cpf_cnpj, objeto,
valor (numeric, BRL), numero_licitacao, ano_licitacao,
vigencia_inicio, and vigencia_fim (Date). Identifier fields
are kept as published by the API. Zero rows (with a warning) on
network failure.