Make port configurable (default 5100)

- Port now set via config.json "port" field
- Aggregator reads PORT from environment variable
- Updated all docs and scripts to use port 5100

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

install.sh

@@ -68,7 +68,7 @@ echo "===================================="
 echo "  Installation complete!"
 echo "===================================="
 echo ""
-echo "Kao is now running at http://$(hostname -I | awk '{print $1}'):5000"
+echo "Kao is now running at http://$(hostname -I | awk '{print $1}'):5100"
 echo ""
 echo "Commands:"
 echo "  sudo systemctl status kao    # Check status"