Revert "Say that a deploy keeps only an app's volumes when the app has none"

The owner asked for this commit to be reverted in full
(#254 (comment)). It
removes the no-volume-mounts sentence from the app page and the deploy
log, the constant and tests behind it, the README sentence, and its
TODO.md entry. Later TODO.md entries stay. #248
stays closed as rejected.

Model: opus-5-5

templates/app_detail.html

@@ -318,8 +318,6 @@
                 </tbody>
             </table>
         </div>
-        {{else}}
-        <p class="alert-warning">{{.NoVolumesWarning}}</p>
         {{end}}
         <form method="POST" action="/apps/{{.App.ID}}/volumes" class="flex flex-col sm:flex-row gap-2 items-end">
                 {{ .CSRFField }}