fix: Korrigiere Nginx PHP-FPM Upstream-Konfiguration für Staging

- Fix upstream configuration in staging-nginx container
- Verbessere sed-Befehle zur automatischen Korrektur der PHP-FPM Upstream-Definition
- Behebt 502 Bad Gateway Fehler durch korrekte Verbindung zu staging-app:9000

deployment/docs/README.md

@@ -113,6 +113,7 @@
 
 - **[gitea-runner/README.md](../gitea-runner/README.md)** - Gitea Runner Setup
 - **[.gitea/workflows/production-deploy.yml](../../.gitea/workflows/production-deploy.yml)** - Haupt-Deployment-Pipeline
+- **[.gitea/workflows/system-maintenance.yml](../../.gitea/workflows/system-maintenance.yml)** - Geplante System-Wartung & Paketupdates
 
 ---
 

deployment/docs/guides/deployment-commands.md

@@ -41,6 +41,14 @@ ansible-playbook -i inventory/production.yml \
   playbooks/setup-infrastructure.yml
 ```
 
+### System Maintenance (regelmäßig)
+
+```bash
+cd deployment/ansible
+ansible-playbook -i inventory/production.yml \
+  playbooks/system-maintenance.yml
+```
+
 ---
 
 ## 📋 Alle verfügbaren Playbooks
@@ -77,6 +85,7 @@ ansible-playbook -i inventory/production.yml \
   # Alles ausführen
   ansible-playbook ... troubleshoot.yml --tags all
   ```
+- **`playbooks/system-maintenance.yml`** - Führt Paket-Updates, Unattended-Upgrades und optional Docker-Pruning aus
 
 ### VPN