feat(enums): add SERVICE product type; fix flaky multi-product checkout test

- ProductType::SERVICE for intangible/served products (subscriptions, licences,
  consulting) — no stock, behaves like SIMPLE for cart purposes. Lets hosts
  whose catalogue includes services adopt the package without a value clash.
- it_creates_separate_line_items_for_multiple_products pinned its two prices to
  one_time; without a type the factory randomised it and could mix recurring +
  one-time, tripping MixedCheckoutModeException intermittently.

README.md

@@ -4,7 +4,7 @@
 
 [![Tests](https://github.com/blax-software/laravel-shop/actions/workflows/tests.yml/badge.svg)](https://github.com/blax-software/laravel-shop/actions/workflows/tests.yml)
 [![Tests Count](https://img.shields.io/badge/tests-1409%20passing-success?style=flat-square)](#testing)
-[![Assertions](https://img.shields.io/badge/assertions-3772-blue?style=flat-square)](#testing)
+[![Assertions](https://img.shields.io/badge/assertions-3773-blue?style=flat-square)](#testing)
 [![Latest Version](https://img.shields.io/packagist/v/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
 [![License](https://img.shields.io/packagist/l/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
 [![PHP Version](https://img.shields.io/packagist/php-v/blax-software/laravel-shop.svg?style=flat-square)](https://packagist.org/packages/blax-software/laravel-shop)
@@ -192,7 +192,7 @@ booking, Stripe sync and the event surface — so host applications can lean
 on the behaviour with confidence.
 
 ```
-Tests: 1409, Assertions: 3772
+Tests: 1409, Assertions: 3773
 ```
 
 CI runs the full suite on every push (see the badge above). To run it

src/Enums/ProductType.php

@@ -19,6 +19,13 @@ enum ProductType: string
      * the borrow → extend → return flow.
      */
     case LOANABLE = 'loanable';
+    /**
+     * Service: an intangible/served product (subscriptions, access licences,
+     * consulting) with no physical stock. Behaves like SIMPLE for cart/stock
+     * purposes; the distinct type just lets hosts and reporting tell goods
+     * from services apart.
+     */
+    case SERVICE = 'service';
 
     public function label(): string
     {
@@ -31,6 +38,7 @@ enum ProductType: string
             self::VARIATION => 'Variation',
             self::POOL => 'Pool',
             self::LOANABLE => 'Loanable',
+            self::SERVICE => 'Service',
         };
     }
 }

tests/Feature/Checkout/CartCheckoutSessionTest.php

@@ -234,6 +234,7 @@ class CartCheckoutSessionTest extends TestCase
             'unit_amount' => 1000,
             'currency' => 'USD',
             'is_default' => true,
+            'type' => 'one_time',
         ]);
 
         ProductPrice::factory()->create([
@@ -242,6 +243,7 @@ class CartCheckoutSessionTest extends TestCase
             'unit_amount' => 2000,
             'currency' => 'USD',
             'is_default' => true,
+            'type' => 'one_time',
         ]);
 
         $this->cart->addToCart($product1, 2);