Implement session management/authentication to access data post-verification

Description

After the session management has been implemented in the API, the frontend should be adapted to use it.

Further details

The frontend should access the "secret" authentication-required endpoint as implemented in the blocking ticket.

Task list

• Implement required code to accept authentication information and persist it for a user.
• Session information is only held in Typescript memory (e.g. state) - not in cookies or local storage.
• Update the verification pop-up to display "secret" information on a success.

Acceptance criteria

• Correctly submitted user information results in frontend authentication, which persists for a user, and can access fake secret information from the API.

Links/references