HANOVER, Germany — German Chancellor Friedrich Merz and Brazilian President Luiz Inácio Lula da Silva pledged to deepen political and economic ties between their countries in response to the increasingly unstable global order. The leaders and members of their governments on Monday signed off on a series of agreements to increase cooperation on everything from defense to rare earths and renewable energy. Merz also said Germany aimed to double its trade volume with Brazil in the next years.