Enhance APIProduct status to provide discovered policy names in structured format

[eguzki]

Problem

Currently, the frontend (backstage plugin) must parse the AuthPolicy name from the human-readable AuthPolicyDiscovered condition message string. This is fragile and error-prone.

- lastTransitionTime: "2026-02-27T14:30:22Z"
  message: Discovered AuthPolicy toystore targeting HTTPRoute toystore
  reason: Found
  status:"True"
  type: AuthPolicyDiscovered

The function used in frontend:

const parseNameFromMessage = (value: string) => {
    const parts = value.split(' ');
    return parts.length >= 3 ? parts[2] : '';
};

The ask is to enhance the APIProduct status to include discovered policy names in a structured format. Preferably this should be implemented without breaking backwards compatibility, though this is not a strong requirement. Since we're working with v1alpha1 APIs, breaking changes are acceptable according to Kubernetes API conventions.