Add Two-Step Verification for Login & Allow Account Name/Email Changes

Two requests that should be prioritized:

1. Two-step verification (2FA) for login – There's currently no option to enable 2FA. This is a basic security requirement, especially for devices that capture personal data. Without it, accounts are vulnerable to credential-based attacks.

2. Ability to change account name and email – Once an account is created, there's no way to update the display name or email address. Users need this for basic account management (e.g., typo corrections, email migrations).

Both of these are standard security and account features that should be available from day one.