Content-Security-Policy For Element Web

https://github.com/vector-im/element-web#configuration-best-practices

roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-client-element.conf.j2

@@ -12,6 +12,7 @@
 	add_header X-Content-Type-Options nosniff;
 	add_header X-XSS-Protection "{{ matrix_nginx_proxy_xss_protection }}";
 	add_header X-Frame-Options SAMEORIGIN;
+	add_header Content-Security-Policy "frame-ancestors 'none'";
 
 	{% if matrix_nginx_proxy_floc_optout_enabled %}
 		add_header Permissions-Policy interest-cohort=() always;