feat: WAN IP Guard - dynamic DNS updater with WhatsApp notifications

Checks public WAN IP every 5 minutes via systemd timer. On change:
- Updates A-records via DirectAdmin API (login key auth)
- Sends WhatsApp notification via wwebjs-api

systemd/wan-ip-guard.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=WAN IP Guard - Dynamic DNS updater
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+# Change 'your-user' and paths to match your setup
+User=your-user
+EnvironmentFile=/home/your-user/wan-ip-guard/.env
+WorkingDirectory=/home/your-user/wan-ip-guard
+ExecStart=/usr/bin/node /home/your-user/wan-ip-guard/index.js

systemd/wan-ip-guard.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Run WAN IP Guard every 5 minutes
+
+[Timer]
+OnBootSec=1min
+OnUnitActiveSec=5min
+AccuracySec=30s
+Persistent=true
+
+[Install]
+WantedBy=timers.target