fix: preflight Linux service manager

install.sh

@@ -64,6 +64,14 @@ detect_platform() {
   fi
 }
 
+validate_service_manager() {
+  [[ "$PLATFORM" != "linux" || "$NO_SERVICE" == "1" ]] && return 0
+  command -v systemctl >/dev/null 2>&1 \
+    || fail 'systemd is required for a production Linux install; use --no-service only for development'
+  [[ -d /run/systemd/system ]] \
+    || fail 'systemd is not running on this Linux host; use --no-service only for development'
+}
+
 java_major() {
   local java_bin="${1:-java}"
   "$java_bin" -version 2>&1 | awk -F'[".]' '/version/ {print $2; exit}'
@@ -294,10 +302,11 @@ shell_setting() {
 prepare_layout() {
   if [[ "$PLATFORM" == "linux" ]]; then
     ERP_USER="${ERP_SERVICE_USER:-kaidi-erp}"
-    ERP_GROUP="$ERP_USER"
     [[ "$ERP_USER" =~ ^[a-z_][a-z0-9_-]*[$]?$ ]] || fail 'invalid Linux service user name'
     id "$ERP_USER" >/dev/null 2>&1 \
       || useradd --system --home-dir "$INSTALL_ROOT" --shell /usr/sbin/nologin "$ERP_USER"
+    ERP_GROUP="$(id -gn "$ERP_USER" 2>/dev/null)" \
+      || fail "unable to resolve the primary group for Linux service user: $ERP_USER"
     CONFIG_ROOT="${ERP_CONFIG_ROOT:-/etc/kaidi-erp}"
     STATE_ROOT="${ERP_STATE_ROOT:-/var/lib/kaidi-erp}"
     LOG_ROOT="${ERP_LOG_ROOT:-/var/log/kaidi-erp}"
@@ -506,6 +515,7 @@ detect_lan_address() {
 
 main() {
   detect_platform
+  validate_service_manager
   if [[ -z "$INSTALL_ROOT" ]]; then
     if [[ "$PLATFORM" == "linux" ]]; then
       INSTALL_ROOT=/opt/kaidi-erp