Function validate_admin_key_authorization 

fn validate_admin_key_authorization(
    admin: bool,
    account: Option<Address>,
    has_expiry: bool,
    has_limits: bool,
    has_scopes: bool,
) -> Result<()>

Enforce the T6 admin access-key invariants when constructing a key authorization.

Admin keys are key-management only: no expiry, spending limits, or call scopes, and they must be bound to a target account (to prevent cross-account replay). A TIP-1053 witness is still allowed.