- require PHP ~8.4.0 and six-it/pimcore-source ^2.0
- explicit nullable parameter types (PHP 8.4 deprecation)
- route annotations -> attributes, routing type: attribute
- GoogleTagManagerListener: symfony/templating EngineInterface -> Twig\Environment
  (symfony/templating does not exist on Symfony 7)
- dev tools: phpstan 2, phpstan-symfony 2, phpunit 10/11, codeception 5.3,
  module-symfony 3.6; phpstan.neon uses ignoreErrors identifiers
- remove two dead checks reported by phpstan 2
- CI: PHP 8.4 matrix, drop removed security.enable_authenticator_manager option

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>