Method set_default_dns_credential

gateway/src/admin_service.rs:433–447

(
        self,
        request: SetDefaultDnsCredentialRequest,
    )

    }

    async fn set_default_dns_credential(
        self,
        request: SetDefaultDnsCredentialRequest,
    ) -> Result<()> {
        let kv_store = self.state.kv_store();

        // Verify the credential exists
        kv_store
            .get_dns_credential(&request.id)
            .context("dns credential not found")?;

        kv_store.set_default_dns_credential_id(&request.id)?;
        info!("Set default DNS credential: {}", request.id);
        Ok(())
    }

    // ==================== ZT-Domain Management ====================