What can Brown do for you? If you're Parsons Engineering, he can get your bill passed in the Assembly -- but not, thus far, in the Senate.Last week, we reported how former Mayor Willie Brown sponsored a legislative bill that would have changed the state's conflict of interest laws to retroactively overturn a San Francisco city attorney's decision -- and land a $26 million water system job for the gargantuan engineering firm Parsons. Yesterday, the Chronicle lashed out at AB 746 and urged the Sta