Business UI - BRH: Remove return query add on

**NOTE: Email link still needs to be updated before this can be removed from the UI.**

- once auth email is updated to include it in the magic link we can remove it from the middleware

Start by tracing the Business UI authentication email and middleware flow, focusing on the return query and magic-link handling mentioned in the issue. Confirm the auth email includes the required value, then verify the return-query addition is removed from the middleware and the magic-link flow still works.

Written by the indexing model from the issue text.