Show coinbase username like the others

The coinbase username appears in one's profile as "coinbase/username" rather than just "username" like the others. I assume this is because the icon used is a generic bitcoin one, not coinbase's .

Since coinbase is one of the services supported out of the box, it would make sense to give it its own icon and show the username undecorated. The icon would look similar to the HackerNews one, so there's even aesthetical precedent :)

Start at the profile display and the existing service-icon definitions, using the Coinbase profile shown in the issue as the reproduction case. Confirm how the Coinbase username and icon are selected, then make the profile show the undecorated username with a dedicated Coinbase icon and verify the other services remain unchanged.

Written by the indexing model from the issue text.