The owner of the Four Seasons in California’s Napa Valley is selling the recently opened hotel in one of the highest-valued lodging transactions ever, punctuating a year of blockbuster resort sales. Sunstone Hotel Investors Inc., a real-estate investment trust, has agreed to pay about $175 million for the 85-room luxury hotel, according to people familiar with the matter. Real estate advisory firm and investment bank Eastdil Secured marketed the transaction for the seller, property fund manager Alcion Ventures.