Sacramento City Councilwoman Mai Vang has advanced to November’s general election for a California congressional seat, setting up a Democrat-on-Democrat clash against longtime incumbent Rep. Doris Matsui. The 81-year-old congresswoman has held the Sacramento-based seat since the death of her husband, former Rep. Bob Matsui, in 2005. Bob Matsui represented the district since the 1970s. Vang, 41, is one of a slew of Democrats across the nation mounting an explicitly generational challenge in the