Set up Jest tests for frontend and add to GitHub CI

[mentatbot]

This PR adds Jest testing infrastructure for the frontend React application and integrates it with GitHub CI.

Key changes:

• Added Jest and related dependencies for React testing
• Created Jest configuration files
• Added example component and utility tests
• Created a GitHub workflow for frontend checks
• Updated precommit script to run frontend tests when changes are detected

This addresses issue #25 by setting up a comprehensive frontend testing system that will help maintain code quality and prevent regressions as the project evolves.

---

🤖 See my steps and cost here ✨

• Wake on any new activity.

[mentatbot]

Jest Testing Implementation Details

Hello @jakethekoenig! I've set up Jest tests for the frontend and added them to the GitHub CI workflow as requested. Here's an overview of what I've implemented:

1. Testing Infrastructure

• Jest Configuration: Created a Jest config file that supports TypeScript and React components.
• TypeScript Config: Added a Jest-specific TypeScript config to properly handle JSX and other testing requirements.
• Test Setup: Created a setup file that includes Testing Library's DOM matchers for component testing.

2. Example Tests

I've added several example tests to demonstrate different testing patterns:

• Simple Tests: Basic tests to verify Jest is working correctly.
• Component Tests: Tests for React components using Testing Library.
• Utility Tests: Tests for non-UI code like the example data utility.

3. CI Integration

• GitHub Workflow: Created a new workflow file specifically for frontend checks that runs on changes to frontend files.
• Precommit Script: Updated the precommit hook to run frontend tests when frontend files are changed.

4. Next Steps

Some suggestions for further improvements:

• Add more comprehensive tests for existing components
• Consider adding end-to-end tests with Cypress or similar tools for more complete coverage
• Add test coverage reporting

Let me know if you'd like any changes or have questions about the implementation!