feat: add fediverse creator meta tag

Author: foosel

layouts/partials/extend_head.html

@@ -1,4 +1,6 @@
 <link rel="webmention" href="https://webmention.io/foosel.net/webmention" />
 <link rel="pingback" href="https://webmention.io/foosel.net/xmlrpc" />
 
+<meta name="fediverse:creator" content="@foosel@chaos.social" />
+
 <script defer data-domain="foosel.net" src="https://plausible.foosel.net/js/script.js"></script>