feat: Automated failover system with certificate sync and DNS monitoring

Certificate Synchronization (COMPLETE):
- Created cert-push-to-hostinger.sh on srvrevproxy02
- Hourly cron job pushes /etc/letsencrypt/ from srvrevproxy02 to Hostinger
- SSH key authentication (id_ed25519_hostinger) configured
- 22MB of Let's Encrypt certificates synced successfully
- Automatic nginx reload on Hostinger after sync
- Log: /var/log/cert-push-hostinger.log

DNS Failover Monitor (READY):
- Python script: dns-failover-monitor.py on Hostinger
- INWX API integration for automatic DNS updates
- Health monitoring every 30s, failover after 3 failures (90s)
- Systemd service with auto-restart
- Setup script: setup-inwx-env.sh for INWX credentials
- Log: /var/log/dns-failover.log

Architecture:
- Primary: srvrevproxy02 (10.0.0.29) - Certificate source
- Secondary: Hostinger (72.62.39.24) - Failover target
- Nginx on Hostinger now uses flow.egonetix.de certificate

Next Steps:
- Run /root/setup-inwx-env.sh on Hostinger
- Enter INWX credentials
- Start monitoring: systemctl start dns-failover

docker-compose.yml

@@ -102,7 +102,7 @@ services:
     container_name: trading-bot-postgres
     restart: unless-stopped
     ports:
-      - "5432:5432"
+      - "55432:5432"
     environment:
       TZ: Europe/Berlin
       POSTGRES_DB: trading_bot_v4