fix(orders): enforce configured expiry

Apply the configured order lifetime to all checkout flows and close unpaid orders once their expiry is reached.

src/Credits/BalanceServiceCharge.php

@@ -326,7 +326,7 @@ trait BalanceServiceCharge {
 			'status'         => \AKSRT\Payment\Order::STATUS_PENDING,
 			'payment_method' => $payment_method,
 			'note'           => is_string($note) ? $note : '',
-			'expires_at'     => gmdate('Y-m-d H:i:s', time() + 30 * MINUTE_IN_SECONDS),
+			'expires_at'     => \AKSRT\Settings\PaymentRuntime::get_order_expiry_at(),
 		]);
 		if ($order_number === '') {
 			return new \WP_Error('aksrt_order_create_failed', __('创建订单失败', 'aksrt'), ['status' => 500]);