Cooking for one. As with a handful of other activities — eating out at restaurants, going to the theater, catching a new film — cooking for ourselves isn’t something most of us plan for, let alone celebrate. Still, we’ve all been there. Because everyone has to eat, right? In her excellent new cookbook, “Solo: A Modern Cookbook for a Party of One,” chef Anita Lo tackles the stigma and challenges when it comes to fending for ourselves in the kitchen.