Feature/sso 04 tests

[jokabuyasina]

Description

This PR adds comprehensive test coverage for the SSO feature, including backend unit tests, security tests, and end-to-end tests.

This is PR #4 of 5 in the SSO feature split (tests only).

Summary by CodeRabbit

• New Features

  • SSO/SAML: per-organization SSO configuration, domain-based routing, auto-enrollment, admin UI and audit logging.

• Security

  • Stricter SSO metadata URL validation and tightened SSO permission checks.
  • Logs now redact sensitive identifiers.

• Improvements

  • Expanded end-to-end and unit tests for SSO and auth flows.
  • Minor translation updates and test robustness fixes.

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