Update ISO installer tiers and backend deployment

ansible/roles/cezen-backend/files/cezen-api.service

@@ -0,0 +1,20 @@
+[Unit]
+Description=Nexus One AI Management API
+After=network-online.target ollama.service
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=cezen
+WorkingDirectory=/opt/cezen/backend
+Environment="CEZEN_DATA=/opt/cezen/data"
+Environment="OLLAMA_URL=http://localhost:11434"
+Environment="PATH=/opt/cezen/backend/venv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin"
+ExecStart=/opt/cezen/backend/venv/bin/uvicorn main:app --host 0.0.0.0 --port 8080 --workers 2
+Restart=always
+RestartSec=5
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target