The Commerce Department reported Thursday that retail sales rose 0.3% in November after falling 0.3% in October. Retail spending over the past 12 months has grown 3.7%, in line with modest economic growth. Even as many Americans struggle to find jobs and pay bills, one sector of the economy has been resilient in this weak economic environment. Wealthy Americans are continuing to spend their money and Web sites like Gilt — a flash sales site that offers discounts on designer apparel and jewelry as well as deals on exotic vacations, restaurants, Broadway shows and gym memberships — has experienced a surge in sales as high-end consumers chose online shopping over brick-and-mortar stores.