Oil prices fell and U.S. stock-index futures jumped Sunday after President Donald Trump said the U.S. has agreed to a peace deal with Iran, apparently ending months of hostilities that shut the Strait of Hormuz and sent the global economy into an oil shock. “The Deal with the Islamic Republic of Iran is now complete,” Trump said in a social-media post late Sunday. “Congratulations to all! I hereby fully authorize the toll free opening of the Strait of Hormuz, and, simultaneously herewith, authorize the immediate removal of the United States Naval blockade. Ships of the World, start your engines. Let...