- Add ConsumeTOTPRecoveryCode to UserRepository for atomic read-verify-update
- Update TOTPService.VerifyTOTP to prefer atomic consumption when available
- Update AuthService.verifyTOTPCodeOrRecoveryCode with same pattern
- Fix critical bug: ConsumeTOTPRecoveryCode now correctly returns consumed=false on mismatch
- Maintain backward compatibility: falls back to non-atomic path if repo doesn't implement interface
- Add comprehensive unit tests for atomic consumption path
Refs: review-fix-closure-2026-05-28 TOTP recovery code atomicity