It only happens once in a lune bleue, so point your Citroen to 1308 Slocum Street in the Design District, where decorator Jan Showers is having a red-tag moment — and only through this Friday. What's marked down? Murano glass lamps, French '40s chairs, an Aldo Tura bar cart, even a Jean Pascaud sofa. Can't promise the rarer bits will still be there by the time you see this, but you'll find ...