As if the 49ers and Seahawks needed more spice to their rivalry, the Niners have added a dash of cayenne pepper.Just days before the 2013 season opener against the Green Bay Packers this Sunday – and less than two weeks before the 49ers and Seahawks meet in Week 2 – the 49ers have snatched wide receiver Chris Harper from Seattle's practice squad and signed him to a three-year deal.Harper, drafted in the fourth round by Seattle out of Kansas State this April, was cut by the 'Hawks this past weekend, but then stashed on their practice squad. San Francisco, which already was carrying five receivers on its roster, then acted quickly to sign him – an act that required the 49ers to put Harper on their 53-man active roster. The Niners were able to make the move by trading linebacker Cam Johnson to the Colts Monday, clearing a spot for Harper.Ian Rapoport of NFL.com reported the Seahawks "fought like crazy" to keep the 49ers from signing Harper, but lost out.Harper, 23, played one season at Oregon before transferring to Kansas State, where he played 51 games, had 132 catches for 1,856 yards and scored 14 TDs. His senior year, he had 57 catches in a run-first offense. In...