Designer, Mindy LavenChristopher Lee Foto More often than not, when the crew makes a discovery during demolition, the news isn’t good. Faulty wiring, asbestos, and dry rot are just a few less-than-ideal surprises. However, rehabilitation of this 1930s Georgian in Long Beach, California, unearthed a happy surprise: A Prohibition-style room tucked behind a pivoting bookcase. “The speakeasy dates back to Prohibition times,” designer Mindy Laven says. “There are even original liquor labels from the 1930s on the walls, along with handwritten notes scribed from past guests.” Everyone was on board with preserving the unexpected find, even if it meant rethinking the layout. “The space where the kitchen was slated to…