Flag URL conflicts between badge server and frontend

:clipboard: **Description**

We now have a lot more frontend routes that exist in the same namespace as the badge routes themselves. I want some kind of check somewhere that complains if we try to add a page to the frontend that conflicts with a badge route, or vice-versa.

TODO: I'm not quite sure about how to approach this yet

The issue names no files, tests, or entry points. First map the frontend routes and badge routes to identify their shared namespace, then decide where a conflict check belongs. Done means adding either kind of route produces a clear complaint when it conflicts with the other.

Written by the indexing model from the issue text.