Former House Speaker Nancy Pelosi’s announcement that she would not seek re-election capped off a decades-long tenure in Congress and the top echelons of the Democratic Party. Now, her departure also sets up a clearer picture of the race to be San Francisco’s next representative in the House — and of how Democrats want to chart the future of their party at a moment of generational change. The two main contenders for Pelosi's district — Scott Wiener, a California state senator, and Saikat