CUB-126: Update Control Center deployment for Go + React

- Updated docker-compose.yml for Go + React + PostgreSQL
- Go backend multi-stage Dockerfile (already existed)
- React frontend multi-stage Dockerfile with nginx SPA config (already existed)
- Kiosk start script and systemd unit
- Deployment README
- .env.example for environment variables

kiosk/control-center-kiosk.service

@@ -0,0 +1,42 @@
+# Control Center Kiosk Service
+# =============================
+# Systemd unit file for auto-starting the Control Center kiosk on boot
+# 
+# Install: sudo cp control-center-kiosk.service /etc/systemd/system/
+# Enable:  sudo systemctl enable control-center-kiosk
+# Start:   sudo systemctl start control-center-kiosk
+# Status:  sudo systemctl status control-center-kiosk
+# Logs:    sudo journalctl -u control-center-kiosk -f
+
+[Unit]
+Description=Control Center Kiosk - Chrome Browser Dashboard
+Documentation=https://code.cubecraftcreations.com/CubeCraft-Creations/Control-Center
+After=graphical-session.target network-online.target
+Wants=network-online.target
+PartOf=graphical-session.target
+
+[Service]
+Type=simple
+ExecStart=/home/overseer/projects/Control-Center/kiosk/start-kiosk.sh http://localhost:3000
+ExecReload=/bin/kill -HUP $MAINPID
+Restart=on-failure
+RestartSec=5
+Environment=DISPLAY=:0
+Environment=XAUTHORITY=/home/overseer/.Xauthority
+WorkingDirectory=/home/overseer/projects/Control-Center
+User=overseer
+Group=overseer
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=control-center-kiosk
+
+# Security hardening
+NoNewPrivileges=true
+ProtectSystem=strict
+ProtectHome=true
+PrivateTmp=true
+ReadWritePaths=/home/overseer/.config/chromium
+ReadWritePaths=/var/log/journal
+
+[Install]
+WantedBy=graphical-session.target