## Description
SuperAdmin impersonation SSO logins no longer create UserSession rows
visible to the customer. Impersonation tokens use a 2-day lifespan
instead of ~2 months, so they naturally evict first and don't linger in
the user's token list.
Server-side detection via Redis value (`'impersonation'` vs `'normal'`)
without changing the `valid_sso_auth_token?` signature. Backward
compatible with in-flight tokens.
Depends on #14556.
## Type of change
- [x] Bug fix (non-breaking change which fixes an issue)
## How Has This Been Tested?
Specs cover: impersonation login skips UserSession creation,
impersonation token has short lifespan, normal SSO login still creates
UserSession row.
## Checklist:
- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules
