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>

authentication/tests.py

@@ -335,3 +335,30 @@ class MfaPageTests(TestCase):
         enrol_mfa(self.user)
 
         self.assertContains(self.client.get(reverse("mfa_reauthenticate")), "otp otp-lg")
+
+
+class ActionBarTests(TestCase):
+    """A form's action bar is drawn when the actions slot has content.
+
+    Regression: it was keyed on `no_visible_fields`, which allauth sets to say a form has
+    no visible *fields* — logout and TOTP deactivate are a bare csrf token plus a button.
+    Keying the bar on it hid the button on exactly the pages that are nothing but a button.
+    """
+
+    def setUp(self):
+        self.user = User.objects.create_user(email="mfa@example.com", password="pw-secret-123")
+        self.client.post(reverse("account_login"), {"login": "mfa@example.com", "password": "pw-secret-123"}, follow=True)
+
+    def test_the_sign_out_page_has_its_button(self):
+        response = self.client.get(reverse("account_logout"))
+
+        self.assertContains(response, "Sign Out")
+        self.assertContains(response, 'type="submit"')
+
+    def test_the_totp_deactivate_page_has_its_button(self):
+        enrol_mfa(self.user)
+
+        response = self.client.get(reverse("mfa_deactivate_totp"))
+
+        self.assertContains(response, "btn-error")
+        self.assertContains(response, 'type="submit"')