design: the panel's backup needs the private key readable, and says so

Owner, 2026-10-11: the key is needed and the panel's archive must be the console's. The box no longer says a certificate file may be left out; Help says the key has to be readable by the panel (group 998 on the host) and that the panel refuses, naming the file, until it is.

check.py: 0 violations; outlines.json unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/assets/panel-redesign/panel/src/backup.html

@@ -12,7 +12,7 @@
         <div class="box">
           <div class="sp-box-head"><span class="sp-no">01</span><h2>Full backup</h2><a class="sp-help" href="help.html#backup" title="Backups, encryption and restore"><i class="ti ti-help-circle"></i></a></div>
           <div class="sp-box-body">
-            <p class="mb-3"><code>data/</code> (database, DKIM keys, credentials), <code>docker-compose.yml</code>, <code>.env</code> and <code>certs/</code> in one archive. The Postfix queue is left out: it cannot be copied reliably while the server is running. So is a certificate file the panel may not read. Restore into an empty project directory and start the <strong>same SelfPost version</strong>. The reverse-proxy vhost is not included.</p>
+            <p class="mb-3"><code>data/</code> (database, DKIM keys, credentials), <code>docker-compose.yml</code>, <code>.env</code> and <code>certs/</code> in one archive. The Postfix queue is left out: it cannot be copied reliably while the server is running. Restore into an empty project directory and start the <strong>same SelfPost version</strong>. The reverse-proxy vhost is not included.</p>
             <form class="sp-form" method="post" action="#">
               <div class="field"><label class="checkbox"><input type="checkbox" name="encrypt" checked> Encrypt with a password (<code>.spbk</code>)</label></div>
               <div class="sp-pair">