[Story]: SCIM conformance testing against Okta and Entra ID

## Summary
Run and document formal SCIM conformance testing against Okta and Microsoft Entra ID, the two IdPs enterprise buyers overwhelmingly standardize on.

## Intent / Source of truth
A SCIM implementation that has never been run against a real IdP's provisioning connector routinely breaks on vendor-specific quirks (attribute casing, pagination cursors, PATCH semantics); this must be proven before any enterprise pilot. Part of [Epic] SCIM 2.0 provisioning and de-provisioning.

## Scope
- [ ] Okta SCIM test-tenant walkthrough: create, update, group sync, deactivate
- [ ] Entra ID provisioning test connection walkthrough covering the same flows
- [ ] Written conformance report with any vendor-specific workarounds documented
- [ ] Regression test suite capturing the discovered edge cases

## Out of scope
- Conformance against other IdPs (Ping, OneLogin, etc.) unless a customer requires it

## Verification
Both IdP test connections show green/successful provisioning cycles end-to-end (create → update → group change → deactivate), captured in the conformance report with screenshots/logs.

## Risk assessment
IdP-specific quirks discovered late in a customer pilot damage trust; front-loading this testing is the whole point of the story.

## AI Usage Declaration
Drafted with AI assistance during the 2026-08-13 cross-repo backlog consolidation and enterprise-readiness research. A human owns intent, verification and consequences.

Start with the Okta SCIM test-tenant walkthrough and the Entra ID provisioning test connection, exercising create, update, group change or sync, and deactivate. Record successful end-to-end cycles in the conformance report with screenshots or logs, document vendor-specific workarounds, and capture discovered edge cases in the regression test suite.

Rédigé par le modèle d'indexation à partir du texte de l'issue.