fix(install): detect enabled services even when failed/stopped during migration

Previously only checked 'is-active' which missed failed/stopped services.
Now checks 'is-enabled' OR 'is-active' to ensure service file gets updated
during v3→v4 migration regardless of service state.

install.sh

@@ -243,11 +243,15 @@ if [ -d "$INSTALL_DIR" ]; then
 
   echo "Updating existing installation at $INSTALL_DIR..."
 
-  # Check if service is running and stop it
+  # Check if service exists (enabled or running) and stop it if active
+  if systemctl is-enabled --quiet nupst 2>/dev/null || systemctl is-active --quiet nupst 2>/dev/null; then
+    SERVICE_WAS_RUNNING=1
     if systemctl is-active --quiet nupst 2>/dev/null; then
       echo "Stopping NUPST service..."
       systemctl stop nupst
-    SERVICE_WAS_RUNNING=1
+    else
+      echo "Service is installed but not currently running (will be updated)..."
+    fi
   fi
 
   # Clean up old Node.js installation files