Add Jest Testing Framework for React Components

[kevin-arch]

Set up Jest to enable unit testing of React components. This will help developers write and maintain testable code.

Tasks:

1. Install Jest and necessary React testing libraries (e.g., React Testing Library).
2. Add a tests/ folder with example tests for an existing component.
3. Add a script in package.json to run tests.
4. Update the README with instructions on running tests.