Los Angeles-based Sweetgreen Inc. (SG) is one of the unlikelier breakout growth stock stories on Wall Street this year. While artificial intelligence (AI) stocks and central bank moves continue to dominate the storyline, Sweetgreen is different – it’s a fast-casual restaurant chain that’s delivered the kind of explosive growth investors more often associate with blockbuster weight-loss drugs or essential AI hardware. Instead, Sweetgreen is more in the Chipotle (CMG) model, with the salad-focused chain offering its consumers a variety of customizable choices, such as frozen yogurts, seasonal se…