President Santiago Peña Palacios of Paraguay addresses the 81st session of the United Nations General Assembly at the UN headquarters, on Wednesday, Sept. 23, 2026. (Dave Sanders/The New York Times) By ADAM B. ELLICK and LAURENCE BLAIR The bank offered Paraguayans a sleek financial future with only a credit card tap and a ping on their phones, complete with tantalizing deals of 40% cash back on credit card purchases. It had splashy sponsorship deals with soccer teams, and ambitions to be a…