Add VPN watchdog with auto-reconnect and disable screen blanking

- Added start_watchdog() function that:
  - Checks VPN every 60 seconds
  - Sends keepalive ping every 5 minutes to prevent idle timeout
  - Auto-reconnects up to 3 times if VPN drops
- Disabled screen blanking in xstartup and after VPN connects
- Removed useless monitor loop that only logged

apps/rego-tunnel/shared/xstartup

@@ -25,6 +25,11 @@ export WEBKIT_DISABLE_DMABUF_RENDERER=1
 openbox &
 sleep 2
 
+# Disable screen blanking and power saving
+xset s off 2>/dev/null || true
+xset -dpms 2>/dev/null || true
+xset s noblank 2>/dev/null || true
+
 # Make script executable and launch in terminal
 chmod +x /shared/cisco-vpn 2>/dev/null || true
 xterm -fa 'Monospace' -fs 11 -bg black -fg white -geometry 130x45+10+10 \