Add PWA bundle config and pwa() Twig function in base template

- Create pwa.yaml with manifest: name, icons (favicon.png), theme color
- Add {{ pwa() }} before stylesheets in base.html.twig head

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

templates/base.html.twig

@@ -76,6 +76,7 @@
             <meta property="og:image" content="https://ticket.e-cosplay.fr/logo.png">
         {% endblock %}
     {% endblock %}
+    {{ pwa() }}
     {% block stylesheets %}{% endblock %}
     {% block javascripts %}
         {{ vite_asset('app.js') }}