Allows SaaS-admin area in non-local/testing envs only when SAAS_ADMIN_TEST_BYPASS=true.
Default false -> production unaffected. Remove after Yandex 360 SSO (Б-1 + DO-4).
TDD: tests/Feature/Middleware/EnsureSaasAdminTest.php (2 passing).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>