Add multi-factor authentication option

[VictrixHominum]

Which feature are you enhancing?
Account security through additional authentication factors

Why is this required?
Even with strong passwords, single-factor authentication remains vulnerable to various attack vectors. Multi-factor authentication adds a critical second layer of security, significantly reducing the risk of unauthorized access even if passwords are compromised.

Any additional context?
Implementation Steps:

1. Extend user model and database schema:

   • Add MFA-related fields to User model in Prisma schema
   • Create tables for storing TOTP secrets and recovery codes
   • Add MFA status and preferences to user profile

2. Implement TOTP authentication:

   • Integrate a TOTP library (like otplib)
   • Create secure secret generation and storage
   • Implement QR code generation for app setup
   • Add verification endpoints for TOTP codes

3. Add email-based verification as fallback:

   • Create email templates for verification codes
   • Implement secure code generation and expiration
   • Add rate limiting for email verification attempts
   • Create verification endpoints for email codes

4. Generate and manage recovery codes:

   • Implement secure recovery code generation
   • Store hashed recovery codes in the database
   • Create UI for viewing and regenerating codes
   • Add recovery code verification flow

5. Create user interfaces:

   • Build MFA setup wizard with clear instructions
   • Add MFA toggle in user settings
   • Create verification screens for login attempts
   • Implement device remembering functionality

6. Update authentication flow:

   • Modify login process to check for MFA requirement
   • Create step-up authentication for sensitive actions
   • Add session handling for MFA-verified sessions
   • Implement remember-device functionality