Looking to drum up some new business, 13-year-old Girl Scout Danielle Lei and her mom set out for a San Francisco medical marijuana clinic on Monday, armed with boxes of Tagalongs, Dulce de Leches and other cookie varieties she and other scouts sell annually. Any patients at The Green Cross with the munchies didn’t stand a chance. In two hours on President’s Day, Danielle sold 117 boxes outside the clinic — people gobbled up all her Dulce de Leches and blazed through the Tagalongs