Re-enable Watchtower with correct Docker API version

Fixes:
- docker-compose/infrastructure.yml:
  - Uncommented Watchtower service
  - Updated image from 1.7.1 to latest
  - Changed DOCKER_API_VERSION from 1.44 to 1.52 (current Docker version)
  - Added default empty value for WATCHTOWER_NOTIFICATION_URL

- scripts/deploy-homelab.sh:
  - Removed "temporarily disabled" note
  - Added Watchtower to infrastructure stack list

- docs/services-overview.md:
  - Updated infrastructure stack count from 7 to 8
  - Added Watchtower to service list

Watchtower now runs successfully with scheduled updates at 4 AM daily

scripts/deploy-homelab.sh

@@ -337,7 +337,7 @@ log_info "  - Pi-hole (DNS Ad Blocker)"
 log_info "  - Dozzle (Log Viewer)"
 log_info "  - Glances (System Monitor)"
 log_info "  - Docker Proxy (Security)"
-log_info "  Note: Watchtower temporarily disabled (Docker API compatibility)"
+log_info "  - Watchtower (Automatic Updates)"
 echo ""
 
 # Copy infrastructure stack