Optional OIDC token storage handle created by the storage module.
Remarks
Uses the shared OIDC contract for the fields supported by DaVinci. The
discovery endpoint is required because DaVinci's current native OIDC path
requires it. openId is intentionally omitted because DaVinci's native
OIDC path does not expose endpoint overrides.
OIDC module configuration nested under DaVinciModules.