Create a Reusable Multi-Stepper Wizard Component in React
Build a reusable multi-step stepper component that accepts an array of child components and renders them one at a time in sequence. Show numbered step indicators with a progress line that fills as steps are completed. Expose onNext and onPrev navigation callbacks to each child so they can validate before proceeding. Support a defaultActive prop to start at a specific step and an unmountOnHide prop to control whether hidden steps stay in the DOM.