Remove email, name, emailRemindersEnabled, and isLocalUser from user JWT
claims, and isLocalUser from link share JWT claims. These fields are never
used from the token - the backend always fetches the full user from the
database by ID, and the frontend fetches user data from the /user API
endpoint immediately after login.
Also simplify GetUserFromClaims to only extract id and username, and
remove the now-unnecessary email override in the frontend's
refreshUserInfo.
e90cb2631d