SAN DIEGO — Adrianne Peterson, the manager of the Rancho Peñasquitos branch of the San Diego Public Library, was actually a little embarrassed by the modest size of her Pride Month display in June. Between staff vacations and organizing workshops for graduating high school students, it had fallen through the cracks and fell short of what she had hoped to offer. Yet the kiosk across from the checkout counter, marked by a Progress Pride rainbow flag, was enough to thrust the suburban library onto