Add ticket status setter and prevent draft text loss

- Set ticket state (Offen / In Bearbeitung / Warten auf Schließen /
  Geschlossen) from the ticket detail page via a live PUT to Zammad;
  pending-close gets a default pending time and the change is synced back
  so it isn't flagged as an external change
- Replace the disruptive meta-refresh with a JS auto-refresh that pauses
  while a text field has unsent content or focus
- Persist reply/new-ticket drafts to localStorage and restore them after
  a reload or accidental navigation

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

templates/new_ticket.html

@@ -9,7 +9,7 @@
   <form method="post" action="{{ url_for('new_ticket_preview') }}"
         class="form attach-form" enctype="multipart/form-data">
     <label>Titel / Betreff
-      <input type="text" name="title" required maxlength="200"
+      <input type="text" name="title" required maxlength="200" data-draft
              placeholder="Kurze Zusammenfassung des Anliegens">
     </label>
     <label>Gruppe
@@ -20,7 +20,7 @@
       </select>
     </label>
     <label>Nachricht
-      <textarea name="body" rows="10" required
+      <textarea name="body" rows="10" required data-draft
                 placeholder="Beschreibe dein Anliegen… (Screenshot mit Strg+V einfügen)"></textarea>
     </label>
     {% include "_attach.html" %}