WASHINGTON — Seeking a shutdown solution, President Donald Trump was expected to announce Saturday that in exchange for money for his promised U.S.-Mexico border wall he was open to trading temporary protections for young people brought to America illegally as children. But it was not clear the offer would trigger a breakthrough, as House Speaker Nancy Pelosi described the anticipated proposals as a “non-starter.” Trump planned a speech from the White House Diplomatic Reception Room at 4 p.m.