introduce lockfile for routes

@dimaMachina and I have implemented lock files for routes on various projects. Need to do the same here. This way if we ever remove a page the CI will complain.

This ticket is more of a reminder for me to do it :)

The issue names no files, tests, or entry points. Start by locating the route definitions and the existing CI configuration, then determine how a route lockfile should be generated and checked; done means CI reports when a page or route is removed unexpectedly.

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