Fix Caddy php_fastcgi root: use /app/public (container path) for SCRIPT_FILENAME

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

ansible/caddy.j2

@@ -21,6 +21,7 @@ ticket.e-cosplay.fr {
     handle {
         root * /var/www/e-ticket/public
         php_fastcgi localhost:4578 localhost:4579 {
+            root /app/public
             lb_policy round_robin
             trusted_proxies private_ranges
         }