Update Docker Registry URLs to HTTPS endpoint (registry.michaelschiemer.de)

- Replace git.michaelschiemer.de:5000 (HTTP) with registry.michaelschiemer.de (HTTPS)
- Update all Ansible playbooks and configuration files
- Update CI/CD workflows to use HTTPS registry endpoint
- Update Docker Compose files with new registry URL
- Update documentation and scripts

Benefits:
- Secure HTTPS connection (no insecure registry config needed)
- Consistent use of HTTPS endpoint via Traefik
- Better security practices for production deployment

deployment/SETUP-GUIDE.md

@@ -408,7 +408,7 @@ docker compose restart registry
 # Test login
 docker login registry.michaelschiemer.de
 # Or if using port:
-docker login git.michaelschiemer.de:5000
+docker login registry.michaelschiemer.de
 ```
 
 **✅ Checkpoint**: All infrastructure stacks running, Gitea accessible, Actions enabled
@@ -665,7 +665,7 @@ curl -k https://michaelschiemer.de/health
 ### Infrastructure
 - [ ] Traefik running and routing HTTPS
 - [ ] PostgreSQL accessible and accepting connections
-- [ ] Docker Registry accessible at git.michaelschiemer.de:5000
+- [ ] Docker Registry accessible at registry.michaelschiemer.de
 - [ ] Gitea accessible at git.michaelschiemer.de
 - [ ] Monitoring stack (Portainer, Grafana, Prometheus) running
 
@@ -741,7 +741,7 @@ ssh-copy-id -i ~/.ssh/production.pub deploy@94.16.110.151
 **Solutions**:
 ```bash
 # Verify credentials
-docker login git.michaelschiemer.de:5000
+docker login registry.michaelschiemer.de
 # Username: admin
 # Password: <your-registry-password>