Add Rector integration for automated PHP code refactoring and downgrading

- Added `rector/rector` as a development dependency for code upgrades and compatibility adjustments.
- Configured a new `rector` script in `composer.json` with a custom PHP 7.4 downgrade rule set.
- Introduced `toPhp7.4.php` configuration file to handle downgrades, including typed properties and union types.

Author: georgedeploy

composer.json

@@ -11,6 +11,7 @@
     "pestphp/pest": "^v3.8.4",
     "pestphp/pest-plugin-type-coverage": "^v3.6",
     "phpunit/phpunit": "^11.5",
+    "rector/rector": "^2.2",
     "vimeo/psalm": "^6.13.1"
   },
   "autoload": {
@@ -51,6 +52,9 @@
       "@mutate",
       "echo '\\n\\n\\033[1;32mPre-commit checks passed!\\033[0m\\n'"
     ],
+    "rector": [
+      "./vendor/bin/rector process --config rector/toPhp7.php"
+    ],
     "test": [
       "./vendor/bin/pest"
     ],

composer.lock

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\Set\ValueObject\DowngradeLevelSetList;
+
+return static function (RectorConfig $rectorConfig): void {
+    // We will process code in this specific directory during CI
+    $rectorConfig->paths([
+        __DIR__,
+    ]);
+
+    // Downgrade rules to make code compatible with PHP 7.2
+    // This handles readonly classes, typed properties, union types, etc.
+    $rectorConfig->sets([
+        DowngradeLevelSetList::DOWN_TO_PHP_74,
+    ]);
+};