feat: migrate test suite from PHPUnit to Pest

- Replace phpunit/phpunit with pestphp/pest ^3.0
- Drop scrutinizer/ocular (incompatible with Pest's symfony/console)
- Add tests/Pest.php with MockeryPHPUnitIntegration trait binding
- Extract namespace-level function stubs (config, route, dir) to
  tests/Overrides.php, loaded via autoload-dev files
- Convert all 5 test classes to Pest closure-based syntax:
  setUp() → beforeEach(), assertions → expect(), skip() for skipped tests
- Delete tests/TestCase.php (logic moved to Pest.php)
- Stubs (TokenStub, User) unchanged

tests/Overrides.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Wearepixel\QuickBooks;
+
+use Wearepixel\QuickBooks\Stubs\User;
+
+function config(string $key): array
+{
+    return [
+        'keys' => [
+            'foreign' => 'user_id',
+            'owner' => 'id',
+        ],
+        'model' => User::class,
+    ];
+}
+
+function route(string $name): string
+{
+    return $name;
+}
+
+function dir(string $path): bool
+{
+    return $path === '/some/valid/path';
+}