docs: add inline documentation where missing

src/Security/BpnAuthenticator.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace App\Security;
 
 use App\BusProNet\ApiClient;
@@ -22,6 +24,13 @@ use Symfony\Component\Security\Http\Authenticator\Passport\SelfValidatingPasspor
 use Symfony\Component\Security\Http\EntryPoint\AuthenticationEntryPointInterface;
 use Symfony\Component\Security\Http\Util\TargetPathTrait;
 
+/**
+ * Authenticates users against the BPN API.
+ *
+ * Validates credentials via BPN's getPersonalData endpoint, creates or updates
+ * local User entities, and retrieves CRM attributes (roles, hotel codes) for
+ * authorization. Passwords are stored encrypted with RSA for subsequent API calls.
+ */
 class BpnAuthenticator extends AbstractLoginFormAuthenticator implements AuthenticationEntryPointInterface
 {
     use TargetPathTrait;