fix: fake systemctl for pured.service + pre-install service file

purevpn-cli checks `systemctl is-active pured.service` to determine if
components are installed. Without systemd this always returns inactive,
triggering endless sudo/reinstall loop and ETXTBSY when trying to overwrite
the running daemon binary.

Fake systemctl returns "active" when pured is listening on :9485, "inactive"
otherwise. Also handles start/stop/disable/daemon-reload as no-ops.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vpn-node/systemctl.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# Fake systemctl for containers — handles pured.service lifecycle without systemd.
+# All other commands are no-ops so purevpn-cli installer steps don't break.
+case "$*" in
+    *"is-active pured"*)
+        nc -z 127.0.0.1 9485 2>/dev/null && echo "active" && exit 0
+        echo "inactive"; exit 1 ;;
+    *"start pured"*)
+        NODE_ENV=production /opt/purevpn-cli/pured-linux-x64 --start &
+        sleep 2; exit 0 ;;
+    *"stop pured"*|*"disable pured"*)
+        pkill -f "pured-linux-x64" 2>/dev/null || true; exit 0 ;;
+    *)
+        exit 0 ;;
+esac