This commit introduces TypeScript support to the project by adding type definitions and necessary configuration files. The main changes include:
- Addition of `tsconfig.json` to configure the TypeScript compiler.
- Creation of type definition files for existing JavaScript modules to enable type checking and IntelliSense.
- Updates to `package.json` to include type information and scripts for building types.
- Test cases to validate the TypeScript integration and ensure type safety.

bot reviewed Feb 10, 2026

This includes updates to the package.json and package-lock.json files to
update dependencies, as well as some changes to the defer.js,
lib/config.js, and lib/util.js files based on the feedback received
about the type information.

The test files were added in a `types` directory in the `test` directory
but the `.gitignore` file was setup to ignore those, and I forgot to add
them in.