Golden Shoulders is a "breakup-proof" band. That's because it consists of Adam Kline and whatever friends are standing near him at any given time. In the past eight years, there have been 48 part-time collaborators, including former members of local bands Cake and Hella, as well as local singer Joanna Newsom. But one time, it was just Kline. Headlining Concert in the Park Friday night, Golden Shoulders will be a four-piece. The concert also features openers Radio Orangevale, Jeepster and Trainwreck Revival (click links for MySpace pages). Back in 2001, Kline formed Golden Shoulders with his friends from Nevada City. Since then they've recorded three albums and one EP, toured the U.S., a