Architecture Kata "Secure calculator"

Develop a calculator application in which individual operations are only available to certain users.

The basic UI of the calculator should look like this:

In addition, the calculator should also contain a user administration function. This can be accessed via a menu, for example. It should be possible to register users, users can log in and out and reassign their password.

When starting the application, users must first log in. [1] If you have forgotten your password, you can have a new one sent to you by e-mail.

After installing the application, there is a default user "admin" (password: "admin") who can create additional users.

Each user is assigned a role. It determines which operations they are allowed to use. Others are grayed out for them.

Data

Rights: Add (A), Subtract (S), Multiply (M), Divide (D), Register user (R)
Roles: Student [A,S], Bachelor [A,S,M], Master [A,S,M,D] Admin [R]
User: Email, password (save as hash only), role

[1] The last user name used is suggested as the user name.