* 🔒 Protect nested theme configuration directories
* Fix WebServerSecurityConfigTest to only assert shipped Apache config
The Nginx dataset read .ddev/nginx/fossbilling-security.conf, which is
dev-only and isn't copied into the CI Docker test image (Dockerfile test
stage only copies src, tests, and composer/phpunit configs, and .ddev is
also dockerignored). file_get_contents returned false there, failing the
Nginx case. Keep the .ddev hardening in place, but only test src/.htaccess.