CVE-2026-105863: Payload authentication token field handling issue

### Impact Under certain field configurations, Payload could include unintended values in the authentication token issued at login. You are affected if: - You use an affected Payload version and have configured a custom field option that maps a field to a reserved authentication claim name. ### Patches Payload now restricts which field configuration options can influence the contents of the authentication token. Users should upgrade payload packages to `>= 3.90.0` or `>= 4.0.0-canary.34`. ### Workarounds There is no complete workaround. Users should upgrade payload packages to `>= 3.90.0` or `>= 4.0.0-canary.34`.