feat: stabilize multi-region runtime sync and worker orchestration

domain-api/deploy/systemd/domain-worker@.service

@@ -0,0 +1,21 @@
+[Unit]
+Description=domainCheck Worker Instance %i
+After=network.target redis.service postgresql.service
+
+[Service]
+Type=simple
+WorkingDirectory=/opt/domaincheck/current/domainCheck
+EnvironmentFile=-/etc/default/domaincheck-worker-%i
+Environment="WORKER_MODE=linux-systemd"
+Environment="QT_QPA_PLATFORM=offscreen"
+ExecStart=/opt/domaincheck/domainCheck/.venv/bin/python /opt/domaincheck/current/domainCheck/detect_worker.py
+Restart=always
+RestartSec=5
+LimitNOFILE=65535
+TasksMax=infinity
+SyslogIdentifier=domaincheck-worker@%i
+User=www
+Group=www
+
+[Install]
+WantedBy=multi-user.target