[WIP] Evaluate updates to modernize the project

[Copilot]

Modernization Plan for Big Presentation System

Based on analysis, the following updates are needed to modernize this multiple-years-old project:

• Update Jest from v29.7.0 to v30.2.0 (latest major version)
• Update jest-environment-jsdom from v29.7.0 to v30.2.0
• Add ESLint as a dev dependency (currently only had config file)
• Update ESLint config from legacy format (.eslintrc.js) to flat config (eslint.config.js)
• Update Node.js version matrix in GitHub Actions (add 22.x LTS, remove 18.x which EOLs April 2025)
• Update ECMAScript version in ESLint config from ES2018 to modern ES2022
• Add lint script to package.json
• Add linting step to GitHub Actions workflow
• Update @testing-library/dom from 10.4.0 to 10.4.1
• Update @testing-library/jest-dom from 6.1.5 to 6.9.1
• Update jest.config.js to use ES module syntax
• Fix test compatibility with jsdom updates
• Run all tests to ensure nothing breaks - All tests passing ✓

Original prompt

Evaluate updates that would modernize this project as it's multiple years old.

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