McpService.enforceBasicLoginGate re-implements AuthController.login's pre-token
SSO/MFA gate; silent drift would re-open the bypass. Add an AST contract test
(comments stripped) asserting BOTH method bodies contain validateSsoEnforcement,
the EE-MFA require, and checkMfaRequirements — so dropping the gate from either
side fails CI. Test-only (no core/auth refactor).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>