Simple Express Healthcheck Middleware

express-healthcheck is a lightweight middleware designed to provide basic health check endpoints for Express.js applications. Released as version 0.1.0 over ten years ago (last published in March 2016), the package is currently unmaintained and effectively abandoned by its original author. It offers a minimal interface to expose an uptime metric and allows for custom `healthy` and `test` functions to provide more application-specific health status, returning a 200 status code with a JSON payload. Unlike more modern and actively maintained health check libraries, it lacks features such as detailed dependency checks, async/await support, built-in security mechanisms, or explicit ESM compatibility, making it suitable only for extremely simple monitoring scenarios or as a historical reference.