It is unlikely that Ikea could alert shoppers to its increasing digital presence by changing its name to iKea, trademark laws being what they are. Perhaps the next best thing is what the Ikea United States division plans to announce on Monday: an initiative centered on what executives call their first interactive seasonal catalog. The 31-page catalog, known as Celebrate Brilliantly, is being introduced in time for Thanksgiving and the Christmas shopping season. It can be read and watched on a section of the Ikea U.S. Web site, ikea-usa.com/celebrate.