It’s not every person who’s thankful for being hit by a car. Of course, it’s also not every person who can go from sleeping on park benches to starting and owning multiple businesses in less than five years. Tammy Powers, as it happens, is not most people. The entrepreneur behind A Tran’s’ Bay Bike Shop and Tammy’s Chicken N’ Waffles on Treasure Island, Powers moved to San Francisco back in 2010 in order to get gender reassignment surgery – she uses the term “transform” –…