fix: pressing enter key reloads enter username page

[nathantew14]

Describe your changes

Added a hidden text field so the page is not reloaded when "enter" is pressed, which is a quirk as described here

Issue ticket number and link

https://github.com/climbjios-sg/climbjios-app/issues/250

Screenshots (if appropriate):

Checklist before requesting a review

• Did yarn test in backend directory