build: require signing identity for mac packaging

scripts/package-mac-app.sh

@@ -88,7 +88,7 @@ fi
 echo "⏹  Stopping any running Clawdis"
 killall -q Clawdis 2>/dev/null || true
 
-echo "🔏 Signing bundle (ad-hoc by default; set SIGN_IDENTITY for real cert)"
-SIGN_IDENTITY="${SIGN_IDENTITY:--}" "$ROOT_DIR/scripts/codesign-mac-app.sh" "$APP_ROOT"
+echo "🔏 Signing bundle (auto-selects signing identity if SIGN_IDENTITY is unset)"
+"$ROOT_DIR/scripts/codesign-mac-app.sh" "$APP_ROOT"
 
 echo "✅ Bundle ready at $APP_ROOT"