Reformatted the ESLint configuration file to use consistent array/object formatting and removed unnecessary quotes from rule names. No functional changes were made; this improves maintainability and clarity. Other config files had only minor formatting updates.
Modernizes test and lint scripts in package.json to use Vitest, Prettier, and ESLint directly. Updates devDependencies to latest versions. Adds a tsconfig.json for type checking and editor support. Improves test mocking in performance.test.js and updates documentation in README.md to reflect new test commands. Cleans up unused options in vitest.config.js.