access control pages plugin middleware

> I was actually thinking we should probably be using the access control pages plugin middleware to enforce the JWT authentication at an application level so it "defaults closed" instead of open. I think that's a more secure approach. Otherwise when you first deploy the project it is completely open to the world potentially exposing your database. With the middleware you would have to explicitly set the relevant environment variables from Zero Trust and only then will you be able to access it.

_Originally posted by @johtso in https://github.com/JacobLinCool/d1-manager/issues/50#issuecomment-2037606017_

Start by locating the application's current authentication and request middleware, then review how Cloudflare Pages access control and Zero Trust environment variables would integrate with it. Confirm the intended default-closed behavior and document the configuration and verification steps needed to ensure unauthenticated access is rejected.

Written by the indexing model from the issue text.