- Created TwoFactorHandler with SetupTwoFactor, VerifyTwoFactor, DisableTwoFactor, GetTwoFactorStatus
- Added routes: POST /auth/2fa/setup, POST /auth/2fa/verify, POST /auth/2fa/disable, GET /auth/2fa/status
- Updated LoginResponse DTO to include requires_2fa flag
- Updated Login handler to check 2FA status and return requires_2fa flag when enabled
- Reused existing TwoFactorService (already had QR generation and TOTP verification)
- Added VerifyTOTPCode helper method to TwoFactorService
- All endpoints properly authenticated with RequireAuth middleware
Phase: PHASE-1
Priority: P0
Progress: 4/267 (1.5%)
8592b3c76b