add php cs fixer

.php-cs-fixer.dist.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpCsFixer\Config;
+use PhpCsFixer\Finder;
+
+return (new Config())
+    ->setRiskyAllowed(false)
+    ->setRules([
+        '@auto' => true
+    ])
+    // 💡 by default, Fixer looks for `*.php` files excluding `./vendor/` - here, you can groom this config
+    ->setFinder(
+        (new Finder())
+            // 💡 root folder to check
+            ->in(__DIR__)
+            // 💡 additional files, eg bin entry file
+            // ->append([__DIR__.'/bin-entry-file'])
+            // 💡 folders to exclude, if any
+            // ->exclude([/* ... */])
+            // 💡 path patterns to exclude, if any
+            // ->notPath([/* ... */])
+            // 💡 extra configs
+            // ->ignoreDotFiles(false) // true by default in v3, false in v4 or future mode
+            // ->ignoreVCS(true) // true by default
+    )
+;

flake.nix

@@ -14,6 +14,7 @@
           cypress
           php85
           php85Packages.composer
+          php85Packages.php-cs-fixer
           phpunit
         ];
       };