Fast-casual chains like Chipotle and Cava are gaining ground amid the K-shaped economic recovery.Dixie D. Vereen/For The Washington Post via Getty ImagesAmericans are dining out less, favoring quality and value over cheaper choices.Fast-casual chains like Chipotle and Cava are gaining ground amid the K-shaped economic recovery.The Slop Bowl chains thrive with menu innovation, while other fast-casual brands see softer sales.The old recession play…