ISLAND PARK, N.Y. — Republican Ari Brown defeated Democrat David Lobl by a 2-1 margin in a special election for the New York State Assembly’s 20th District seat, as Republicans continue to gain momentum on Long Island and predict victories across the state and nationally next November. “This is just the beginning of a red wave like never before,” Brown said Thursday night, after he won the seat — covering areas including the Five Towns, Island Park, Long Beach and Atlantic Beach — which was vacated by Republican Melissa “Missy” Miller in February, who took a position on the Hempstead...