fix(devops): repair phpstan config so static analysis runs again

- container_xml_path -> containerXmlPath (phpstan-symfony v2 rename); the old
  key made phpstan abort with an invalid-configuration error, so analysis
  silently never ran
- add the missing tests/doctrine_object_manager.php loader
- drop a stale ignoreErrors pattern

phpstan now runs and surfaces 42 pre-existing level-5 errors (tracked separately).

phpstan.neon

@@ -7,8 +7,6 @@ parameters:
     paths:
         - src
     symfony:
-        container_xml_path: var/cache/dev/App_KernelDevDebugContainer.xml
+        containerXmlPath: var/cache/dev/App_KernelDevDebugContainer.xml
     doctrine:
         objectManagerLoader: tests/doctrine_object_manager.php
-    ignoreErrors:
-        - '#Call to an undefined method Doctrine\\ORM\\QueryBuilder::#'

tests/doctrine_object_manager.php

@@ -0,0 +1,16 @@
+<?php
+
+// Loader used by phpstan-doctrine to resolve entity metadata for static analysis.
+// Boots the Symfony kernel and returns the default EntityManager.
+
+use App\Kernel;
+use Symfony\Component\Dotenv\Dotenv;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+(new Dotenv())->bootEnv(__DIR__ . '/../.env');
+
+$kernel = new Kernel($_SERVER['APP_ENV'] ?? 'dev', (bool) ($_SERVER['APP_DEBUG'] ?? true));
+$kernel->boot();
+
+return $kernel->getContainer()->get('doctrine')->getManager();