feat(jmri): headless JMRI server with Leviton layout power monitor and X11 GUI mode

- Stable udev device symlinks (/dev/jmri/nce, /dev/jmri/loconet, /dev/jmri/lcc)
- jmri-monitor: polls Leviton Decora Smart switch to start/stop JMRI automatically
  - Quiet hours 1-10 AM (no polling)
  - 30s off-delay before shutdown
- LCRR config cloned from Gitea (ssh://gitea.mk-labs.cloud:2221/rblundon/LCRR.git)
- ~/.jmri symlinked to LCRR repo for GitOps config management
- jmri-gui: X11 remote GUI access (PanelPro/DecoderPro) via ssh -X as jmri user
  - Stops daemon, launches GUI, restarts daemon on exit if layout still on
- jmri user gets login shell + SSH key for GUI sessions
- Full JRE installed (openjdk-21-jre) for AWT/X11 support

ansible/roles/jmri/templates/jmri-monitor.service.j2

@@ -0,0 +1,20 @@
+[Unit]
+Description=JMRI LocoNet Traffic Monitor
+Documentation=https://www.jmri.org/
+# Must start after udev has processed devices
+After=systemd-udev-settle.service
+
+[Service]
+Type=simple
+# Runs as root — needs to call systemctl start/stop jmri.service
+User=root
+ExecStart=/usr/local/bin/jmri-monitor
+Restart=always
+RestartSec=10
+
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=jmri-monitor
+
+[Install]
+WantedBy=multi-user.target