Last spring, Sweetgreen did something shocking, at least insofar as the menu adjustments of a fast-casual salad chain can be described that way: It added fries. In interviews, the company’s “chief concept officer,” Nicolas Jammet, paid lip service to “reevaluating and redefining fast food,” but I suspect that Sweetgreen was also “reevaluating and redefining” how to make money in a world that appeared poised to move on from buying what the company was trying to sell. In the first two months of last year, Sweetgreen’s stock price had declined more than 30 percent. The company had already made significant changes, dropping seed oils, adding “protein plates,” and hiring a bunch of robots in an apparent effort to cater to the early 2020s’ three defining dining trends: the MAHA movement, the protein fixation, and the push to cut costs by eliminating human labor. But not even air-fried potatoes could stop Sweetgreen’s free fall. In August, with operational losses reaching $26.4 million, the chain fired workers, and also the fries. As the year ended, Nathaniel Ru, who …