feat: Add phpstan and ecs code linting

composer.json

@@ -2,7 +2,7 @@
   "name": "nystudio107/craft-icalendar",
   "description": "Tools for parsing & formatting the RFC 2445 iCalendar (.ics) specification",
   "type": "craft-plugin",
-  "version": "4.0.1",
+  "version": "4.0.2",
   "keywords": [
     "craft",
     "cms",
@@ -26,6 +26,16 @@
     "craftcms/cms": "^4.0.0",
     "johngrogg/ics-parser": "^3.0.0"
   },
+  "require-dev": {
+    "craftcms/ecs": "dev-main",
+    "craftcms/phpstan": "dev-main",
+    "craftcms/rector": "dev-main"
+  },
+  "scripts": {
+    "phpstan": "phpstan --ansi --memory-limit=1G",
+    "check-cs": "ecs check --ansi",
+    "fix-cs": "ecs check --fix --ansi"
+  },
   "config": {
     "allow-plugins": {
       "craftcms/plugin-installer": true,

ecs.php

@@ -0,0 +1,13 @@
+<?php
+
+use craft\ecs\SetList;
+use Symplify\EasyCodingStandard\Config\ECSConfig;
+
+return static function(ECSConfig $ecsConfig): void {
+    $ecsConfig->paths([
+        __DIR__ . '/src',
+        __FILE__,
+    ]);
+    $ecsConfig->parallel();
+    $ecsConfig->sets([SetList::CRAFT_CMS_4]);
+};

phpstan.neon

@@ -0,0 +1,7 @@
+includes:
+    - %currentWorkingDirectory%/vendor/craftcms/phpstan/phpstan.neon
+
+parameters:
+    level: 5
+    paths:
+        - src