feat: Add systemd service for DSS API

Add dss-api.service to run the API server on port 8000.
Replaces the old design-system-mcp service.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

infra/dss-api.service

@@ -0,0 +1,21 @@
+[Unit]
+Description=DSS API Server
+Documentation=https://github.com/overbits/dss
+After=network.target
+
+[Service]
+Type=simple
+User=overbits
+Group=overbits
+WorkingDirectory=/home/overbits/dss
+Environment=PATH=/home/overbits/dss/.venv/bin:/usr/local/bin:/usr/bin:/bin
+Environment=PYTHONPATH=/home/overbits/dss
+ExecStart=/home/overbits/dss/.venv/bin/python -m uvicorn apps.api.server:app --host 127.0.0.1 --port 8000
+Restart=on-failure
+RestartSec=5
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=dss-api
+
+[Install]
+WantedBy=multi-user.target