aMember (site.php): Add Open Graph Meta to Login Page

site.php

<?php

Am_Di::getInstance()->blocks->add('login/form/before', new Am_Block_Base(null, 'og-login', null, function(Am_View $v) {
        $meta = [
            'og:image' => '/path/to/image.png',
        ];

        $out = '';
        foreach ($meta as $property => $content) {
            $out .= sprintf(
                '<meta property="%s" content="%s" />%s',
                Am_Html::escape($property),
                Am_Html::escape($content),
                "\n"
            );
        }

        $v->placeholder("head-start")->append($out);

}));