Fix and update tests to work with Vite/Vitest after migration from CRA

After migrating from Create React App (CRA) and react-scripts to Vite, update the project's test setup so that all tests work smoothly with the Vitest-supported test framework.

Tasks

• Replace any test dependencies and configs from CRA/react-scripts with Vite-compatible alternatives
• Ensure all existing tests run and pass using Vitest or upgraded testing framework instead of usin jest
• Update documentation for running tests with Vitest
• Address any issues or incompatibilities found during the migration

This will ensure the project maintains test coverage and reliability after switching to Vite.