implementation of the Email add on

Web/templates/admin_borrowings.html

@@ -195,6 +195,13 @@
         <textarea id="damage-reason" name="damage_reason" rows="5" required style="width:100%; padding:10px; border:1px solid #ddd; border-radius:6px; resize:vertical;" placeholder="Beschreiben Sie kurz den Schaden oder die Zerstörung."></textarea>
       </div>
 
+      {% if email_service_enabled %}
+      <div style="margin-bottom:16px;">
+        <label for="invoice-recipient-email" style="display:block; font-weight:700; margin-bottom:6px;">Empfänger-E-Mail für den PDF-Versand</label>
+        <input id="invoice-recipient-email" name="recipient_email" type="email" style="width:100%; padding:10px; border:1px solid #ddd; border-radius:6px;" placeholder="name@beispiel.de">
+      </div>
+      {% endif %}
+
       <div style="display:flex; flex-wrap:wrap; gap:16px; align-items:center; margin-bottom:18px;">
         <label style="display:flex; align-items:center; gap:8px;">
           <input type="checkbox" name="mark_destroyed" checked>
@@ -208,7 +215,10 @@
 
       <div style="display:flex; justify-content:flex-end; gap:10px;">
         <button type="button" class="btn btn-secondary" onclick="closeInvoiceModal()">Abbrechen</button>
-        <button type="submit" class="btn btn-danger">PDF-Rechnung erstellen</button>
+        <button type="submit" class="btn btn-outline-danger" name="delivery" value="pdf">Nur PDF herunterladen</button>
+        {% if email_service_enabled %}
+        <button type="submit" class="btn btn-danger" name="delivery" value="email">PDF per E-Mail senden</button>
+        {% endif %}
       </div>
     </form>
   </div>