Expect-CT Header Middleware

The `expect-ct` package provides Express middleware for setting the deprecated Expect-CT HTTP response header. This header was designed to enforce Certificate Transparency (CT) requirements by instructing browsers to expect valid Signed Certificate Timestamps (SCTs) for a website's TLS certificates. However, the Expect-CT header itself has been deprecated by major browsers (e.g., Chrome removed support in version 107 in October 2022) as Certificate Transparency is now a baseline requirement enforced by default across all publicly trusted certificates. As such, this middleware, currently at version 1.0.0 (though `1.0.1` is on npm, published 3 years ago), offers minimal practical security benefit for modern web applications. The Helmet.js project, which originally included this functionality, removed `expect-ct` from its default middlewares in Helmet v5 due to its obsolescence.