Add PHP CS Fixer and PHPStan max to CI; remove abandoned GoutteFactory

- Add friendsofphp/php-cs-fixer ^3.75 and phpstan/phpstan ^2.0 to
  require-dev; add .php-cs-fixer.dist.php (@Symfony ruleset with
  phpdoc_to_comment ignored_tags) and phpstan.neon (level max,
  treatPhpDocTypesAsCertain: false)
- Run CS Fixer and PHPStan in every CI matrix job alongside tests
- Add composer scripts: cs, cs-check, phpstan
- Add .php-cs-fixer.cache to .gitignore
- Fix all PHPStan max violations across src/: add return/param types,
  narrow mixed config values with is_string()/is_array() guards,
  use TaggedNodeInterface for scenario tag access in SessionsListener
- Remove GoutteFactory and its spec — the goutte driver and its
  underlying client library are abandoned

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

src/Behat/MinkExtension/ServiceContainer/Driver/SahiFactory.php

@@ -15,26 +15,17 @@ use Symfony\Component\DependencyInjection\Definition;
 
 class SahiFactory implements DriverFactory
 {
-    /**
-     * {@inheritdoc}
-     */
-    public function getDriverName()
+    public function getDriverName(): string
     {
         return 'sahi';
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function supportsJavascript()
+    public function supportsJavascript(): bool
     {
         return true;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function configure(ArrayNodeDefinition $builder)
+    public function configure(ArrayNodeDefinition $builder): void
     {
         $builder
             ->children()
@@ -48,29 +39,27 @@ class SahiFactory implements DriverFactory
     }
 
     /**
-     * {@inheritdoc}
+     * @param array<string, mixed> $config
      */
-    public function buildDriver(array $config)
+    public function buildDriver(array $config): Definition
     {
         trigger_deprecation('friends-of-behat/mink-extension', '2.8.0', 'Configuration for the "sahi" driver is deprecated, since the client implementation has been abandoned. Support for it will be removed in the next major version of this extension.');
 
         if (!class_exists('Behat\Mink\Driver\SahiDriver')) {
-            throw new \RuntimeException(
-                'Install MinkSahiDriver in order to use sahi driver.'
-            );
+            throw new \RuntimeException('Install MinkSahiDriver in order to use sahi driver.');
         }
 
-        return new Definition('Behat\Mink\Driver\SahiDriver', array(
+        return new Definition('Behat\Mink\Driver\SahiDriver', [
             '%mink.browser_name%',
-            new Definition('Behat\SahiClient\Client', array(
-                new Definition('Behat\SahiClient\Connection', array(
+            new Definition('Behat\SahiClient\Client', [
+                new Definition('Behat\SahiClient\Connection', [
                     $config['sid'],
                     $config['host'],
                     $config['port'],
                     $config['browser'],
                     $config['limit'],
-                )),
-            )),
-        ));
+                ]),
+            ]),
+        ]);
     }
 }