Extends

1. Create a Shape base class with:
   • Public field: color (string)
   • Constructor (color: string)
2. Create a Circle class that extends Shape with:
   • Public field: radius (number)
   • Constructor (color, radius) that initializes the parent via super(color)
3. Create a Rectangle class that extends Shape with:
   • Public fields: width (number), height (number)
   • Constructor (color, width, height) that calls super(color)
4. Export all three: export { Shape, Circle, Rectangle }

Fixtures and success criteria

const circle = new Circle('red', 5)
const rectangle = new Rectangle('blue', 10, 20)

• circle.color === 'red' and circle.radius === 5
• rectangle.color === 'blue', width === 10, height === 20
• circle instanceof Shape and rectangle instanceof Shape are both true (each subclass is substitutable as a Shape)