Enterprise Security Configurations can be enforced for organization admins [GA]

### Value Prop
Enterprise admins can enforce security configurations across organizations and repositories, preventing both organization and repository admins from overriding settings defined at the enterprise level. This gives security and compliance teams a reliable, consistent way to apply mandatory policies at scale.

### Expected Outcome
Enterprises gain end-to-end control over their security posture, reducing the risk of policy drift caused by configuration changes at the organization or repository level. With enforceable security configurations, teams can meet compliance requirements with confidence and spend less time auditing or correcting downstream overrides.

The issue names no implementation files, tests, or entry points. Start by reviewing the roadmap requirements and identifying the product area that owns enterprise security configurations. Done means enterprise administrators can enforce configurations across organizations and repositories, with lower-level administrators unable to override them.

索引モデルが issue の本文から書いたものです。