fix(mac): fail fast without full Xcode (#120909)

scripts/lib/swift-toolchain.sh

@@ -4,6 +4,14 @@ REQUIRED_SWIFT_TOOLS_MAJOR=6
 REQUIRED_SWIFT_TOOLS_MINOR=2
 
 require_swift_toolchain() {
+  if ! xcrun xcodebuild -version >/dev/null 2>&1; then
+    echo "ERROR: OpenClaw macOS app packaging requires a full Xcode developer directory." >&2
+    echo "       Command Line Tools do not include the required SwiftUI macro plugins." >&2
+    echo "       Use: sudo xcode-select -s /Applications/Xcode.app/Contents/Developer" >&2
+    echo "       Or set: DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer" >&2
+    return 1
+  fi
+
   local swift_version
   if ! swift_version="$(swift --version 2>&1)"; then
     printf '%s\n' "$swift_version" >&2