By Claire Cain Miller April 2, 2010 7:54 pm April 2, 2010 7:54 pm Shopping on Gilt, the site with private, limited-time sales, can be a blood sport, with shoppers competing against others for a pair of gold Calvin Klein heels in a size 8. Gilt’s new iPad app, which is already available in the App Store, could give iPad owners a leg up on the competition, and not just because it is mobile so people