feat: graphiti-viz FastAPI 后端 + systemd unit + nginx vhost

查 Graphiti Neo4j → 标准 {nodes,edges} 供 graph-viewer 组件渲染; 六组group_id;
含部署配置(unit/nginx)与 viz.env.example(密钥走⟨secdb⟩不入库); .gitignore 排除 env/vendor/备份

systemd/graphiti-viz.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Graphiti temporal knowledge graph visualization (FastAPI + static frontend)
+After=network-online.target docker.service
+
+[Service]
+Type=simple
+User=mag
+Group=mag
+WorkingDirectory=/www/dk_project/dk_app/graphiti-viz
+EnvironmentFile=/www/dk_project/dk_app/graphiti-viz/viz.env
+ExecStart=/www/dk_project/dk_app/graphiti-viz/.venv/bin/python /www/dk_project/dk_app/graphiti-viz/graphiti_viz.py
+Restart=always
+RestartSec=5
+StandardOutput=append:/www/dk_project/dk_app/graphiti-viz/viz.log
+StandardError=append:/www/dk_project/dk_app/graphiti-viz/viz.log
+
+[Install]
+WantedBy=multi-user.target