fix: update usage instructions to support optional group argument in package installation scripts

packages/install.sh

@@ -3,12 +3,14 @@
 
 set -euo pipefail
 
-if [ $# -ne 1 ]; then
-    echo "Usage: $0 <dotfiles_directory>"
+if [ $# -lt 1 ] || [ $# -gt 2 ]; then
+    echo "Usage: $0 <dotfiles_directory> [group]"
     exit 1
 fi
 
 dotfiles_dir="$1"
+# Optional group argument (e.g., base.txt)
+group_arg="${2:-}"
 # Source shared utilities
 source "$dotfiles_dir/scripts/utils.sh"
 
@@ -101,8 +103,15 @@ install_package_lists() {
 
     # Determine which groups to install
     local selected_groups=()
-    # Determine interactive mode: forced via INTERACTIVE=1 or a real interactive shell
-    if [ "${INTERACTIVE:-0}" -eq 1 ] || is_interactive; then
+    if [ -n "$group_arg" ]; then
+        # Direct install of specified group
+        if [[ " ${package_files[*]} " == *" $group_arg"* ]]; then
+            selected_groups=("$group_arg")
+        else
+            log_error "Unknown package group: $group_arg"
+            exit 1
+        fi
+    else
         echo "Available package groups:"
         for pkg in "${package_files[@]}"; do
             if [ -f "$packages_dir/$pkg" ]; then
@@ -123,9 +132,6 @@ install_package_lists() {
                 fi
             done
         fi
-    else
-        # Non-interactive: install only the base group
-        selected_groups=("base.txt")
     fi
 
     # Loop through selected package lists