Indicate a contact is also a user

DT for web displays a message on the contact record when that contact is a user on DT. This information would be useful when trying to find users of DT and might be better suited as a filter.

Start by tracing the contact record display and the existing user-search or filtering flow in the mobile app. Clarify whether the desired result is an indicator on each contact, a filter for contacts who are users, or both; done means the chosen behavior reliably identifies DT users among contacts.

Written by the indexing model from the issue text.