feat: OnlyOffice Force-Save bei Ctrl+S + private IP erlauben

- forcesavetype in Editor-Config: Ctrl+S speichert sofort zurueck
  zum Server (statt erst beim Schliessen des Dokuments)
- ALLOW_PRIVATE_IP_ADDRESS + ALLOW_META_IP_ADDRESS fuer OnlyOffice
  damit Callbacks an interne Docker-IPs funktionieren

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/office.py

@@ -380,6 +380,7 @@ def onlyoffice_config(file_id):
             'editorConfig': {
                 'callbackUrl': f'{internal_url}/api/files/onlyoffice-callback?key={callback_key}',
                 'mode': 'edit' if can_write else 'view',
+                'forcesavetype': 0,
                 'lang': 'de',
                 'user': {
                     'id': str(user.id),

docker-compose.yml

@@ -21,6 +21,8 @@ services:
     environment:
       - JWT_ENABLED=true
       - JWT_SECRET=${JWT_SECRET_KEY}
+      - ALLOW_META_IP_ADDRESS=true
+      - ALLOW_PRIVATE_IP_ADDRESS=true
     volumes:
       - ./data/onlyoffice/logs:/var/log/onlyoffice
       - ./data/onlyoffice/data:/var/www/onlyoffice/Data