chore: add PHP-CS-Fixer, matching the core config

.github/workflows/ci.yml

@@ -25,6 +25,9 @@ jobs:
       - name: Install dependencies
         run: composer install --no-interaction --prefer-dist --no-progress
 
+      - name: Formatting
+        run: vendor/bin/php-cs-fixer fix --dry-run --diff
+
       - name: Static analysis
         run: vendor/bin/phpstan analyse --no-progress --memory-limit=512M
 

.gitignore

@@ -3,3 +3,4 @@
 .phpunit.result.cache
 .phpunit.cache/
 .DS_Store
+.php-cs-fixer.cache

.php-cs-fixer.dist.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Matches the NimbusCMS core config: conservative, PSR-12-oriented, no
+ * house-style rewrites. Kept identical so official packages format the same way.
+ */
+$finder = PhpCsFixer\Finder::create()
+    ->in([__DIR__ . '/src', __DIR__ . '/tests'])
+    ->append([__FILE__]);
+
+return (new PhpCsFixer\Config())
+    ->setRiskyAllowed(false)
+    ->setRules([
+        '@PSR12'                       => true,
+        'array_syntax'                 => ['syntax' => 'short'],
+        'no_unused_imports'            => true,
+        'ordered_imports'              => ['sort_algorithm' => 'alpha'],
+        'single_quote'                 => true,
+        'trailing_comma_in_multiline'  => ['elements' => ['arrays', 'arguments', 'parameters']],
+        'no_trailing_whitespace'       => true,
+        'no_whitespace_in_blank_line'  => true,
+        'blank_line_after_opening_tag' => true,
+    ])
+    ->setFinder($finder);

composer.json

@@ -20,6 +20,7 @@
         "nimbuscms/nimbus": "dev-main"
     },
     "require-dev": {
+        "friendsofphp/php-cs-fixer": "^3.95",
         "phpstan/phpstan": "^2.2",
         "phpunit/phpunit": "^11.0"
     },
@@ -51,7 +52,9 @@
         "check": [
             "@analyse",
             "@test"
-        ]
+        ],
+        "format": "php-cs-fixer fix",
+        "format:check": "php-cs-fixer fix --dry-run --diff"
     },
     "config": {
         "sort-packages": true