evidence: LONDON — A deal between the U.K. and EU aimed at ending the long-running dispute over post-Brexit trade rules in Northern Ireland finally appears to be within reach, heralded by a flurry of last-minute diplomatic activity. The original agreement — governing trade, regulation and areas of taxation in Northern Ireland and negotiated as a separate protocol to the Brexit withdrawal agreement which set out the terms of the U.K.’s exit from the bloc — was intended to avoid a physical border between Northern Ireland and the EU’s single market in the Republic of Ireland to the south while at the same time not inserting a border between Northern Ireland and the rest of the U.K.