feat: add systemd unit

pkg/hayai.service

@@ -0,0 +1,23 @@
+[Unit]
+Description=An EEW system for Linux
+After=network.target
+StartLimitIntervalSec=60
+StartLimitBurst=4
+
+[Service]
+User=%i
+ExecStart=/usr/bin/hayai
+Restart=on-failure
+RestartSec=1
+SuccessExitStatus=3 4
+RestartForceExitStatus=3 4
+
+# Hardening
+ProtectSystem=full
+PrivateTmp=true
+SystemCallArchitectures=native
+MemoryDenyWriteExecute=true
+NoNewPrivileges=true
+
+[Install]
+WantedBy=multi-user.target