In the gauzy, ruffle-curtained corner of social media known as #grannycore, the past is very much present. Whether it’s in the form of a familiar tufted settee, a floral couch or groovy hook-and-latch rugs, nostalgia has been quietly coalescing into a design trend fueled by the pandemic-era clamor for coziness and aided by a glut of brown furniture and china in secondhand stores.