retainForTerraformAdoption=true adds the required ManageSiteInfrastructure
parameter, conditions the 13 transferred resources and the S3 auto-delete
custom resource on it, applies Retain policies, pins the live dev origin
ID, attaches the deploy boundary and HcpTerraformWorkspace tag, and
narrows the OIDC subject to StringEquals. Normal synthesis is unchanged;
template tests cover both modes.
