Branded is a weekly column devoted to the intersection of marketing, business, design, and culture.Just a few years ago, iRobot, best known as the maker of the Roomba, was riding high, with annual revenue topping $1 billion; Amazon bid $1.7 billion to add it to the e-commerce giant’s home technology business. But that deal fell through, and now the Bedford, Massachusetts-based company has reported plunging revenue and steep losses, and recently warned investors of “substantial doubt” about its “...