San Francisco’s oldest independent coffee roasting company, Graffeo Coffee, has a new owner. Walter A. Haas III, 40, a scion of the family behind Levi Strauss & Co., is the new proprietor of the 90-year-old North Beach staple. He bought a majority stake in the company a few months ago, joining longtime owner and chief roaster Luciano Repetto, 80, who will remain a part of the company. The new owner hopes to steward Graffeo into the future while…