WASHINGTON — Mayor Mamdani’s whiz-kid spin doctor has been accused of pressuring Maine Senate hopeful Graham Platner’s ex political director to lie about the horny oyster farmer’s sexting scandal — and threatened her if she didn’t. Morris Katz, the 27-year-old hot-shot strategist who helped catapult Mamdani to Gracie Mansion, allegedly pressed former Platner campaign staffer Genevieve McDonald to deny the sexting scandal to the press. “Just want to be clear on where we are right now,” Katz wrote to McDonald through a third party, according to messages reported by Bangor Daily News. Graham Platner is in hot water after revelations...