Add installer skill listing

Author: tmusser

install.sh

@@ -2,4 +2,17 @@
 set -eu
 
 SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+
+case "${1:-}" in
+  --list)
+    printf '%s\n' "Available skills:"
+    for skill_file in "$SCRIPT_DIR"/skills/*/SKILL.md; do
+      [ -f "$skill_file" ] || continue
+      skill_dir=${skill_file%/SKILL.md}
+      printf '%s\n' "- ${skill_dir##*/}"
+    done
+    exit 0
+    ;;
+esac
+
 exec python3 "$SCRIPT_DIR/scripts/install_skills.py" "$@"