Usability: 6 second wait for login, with no screen update

[mccalluc]

Running the local docker compose, logging in with admin credentials: there was a ~6 second pause between hitting the button and starting to load the my-data page: Long enough for me to wonder if something was broken. Suggest giving some immediate feedback in the UI so the user knows that action has started: Disabling the button, showing a spinner: Whatever is idiomatic with this design library.