Allen H. Weisselberg, a longtime top executive at Donald J. Trump’s family business who was indicted on tax charges last summer, is nearing a plea deal with prosecutors from the Manhattan district attorney’s office but would not cooperate with a broader investigation into Mr. Trump, according to two people with knowledge of the matter. His plea deal, if finalized, would bring prosecutors no closer to indicting the former president but would nonetheless brand one of his most trusted lieutenants a felon. On Monday, Mr. Weisselberg’s lawyers and prosecutors met with the judge overseeing the case, according to a court database....