There's one public work project that's a cafe, But for a bakery someone would usually just design a room in their house to make it look like a bakery/cafe
The best bakeries I've seen are where a side character only expands their house to 6 x 6 with no other rooms besides the main room, and then fills that room with bakery themed furniture and changes the exterior to make it look like a bakery. This makes the house look like a nice, cozy bakery and not just a room in a house designed to look like a bakery.