Restore the buttons on the sign-out and deactivate pages

The form element drew its action bar only when `no_visible_fields` was unset. That
attribute means the form has no visible *fields* -- logout and TOTP deactivate are
a bare csrf token plus a button -- and says nothing about its actions. So the bar,
and the only button on the page, was hidden on exactly the pages that exist to
offer that button. Sign Out could not be clicked at all.

The bar is now drawn when the actions slot has content, which is the condition
that was meant all along. Tests cover both pages.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

templates/allauth/elements/form.html

@@ -4,13 +4,18 @@
     `id` is not decorative: allauth renders out-of-band forms (webauthn, logout-from-stage)
     and points buttons at them with the HTML `form` attribute. Drop the id and those
     buttons submit nothing.
+
+    The action bar is drawn when the actions slot has something in it — NOT keyed on
+    `no_visible_fields`, which means the form has no visible *fields* (logout is a bare
+    csrf token, and so is TOTP deactivate) and says nothing about its buttons. Keying the
+    bar on it hides the Sign Out button on the very page whose only purpose is that button.
 {% endcomment %}
 <form method="{{ attrs.method }}"
       {% if attrs.id %}id="{{ attrs.id }}"{% endif %}
       {% if attrs.action %}action="{{ attrs.action }}"{% endif %}
       class="space-y-2">
     {% slot body %}{% endslot %}
-    {% if not attrs.no_visible_fields %}
+    {% if slots.actions %}
         <div class="card-actions justify-end pt-3">
             {% slot actions %}{% endslot %}
         </div>