Lindsey Vonn lifts her middle finger in the Southern California sun. Vonn, the Olympic gold medal skier, all-time leader in World Cup downhill wins, and rare figure in her sport whose talent, charisma, and celebrity have transcended the snow-covered slopes, is hiking a canyon near her Beverly Hills home. Not so long ago, this might have seemed unfathomable, as she struggled with not just standard wear and tear that comes from decades of competing at a professional level but swelling and pain