fix: avoid stderr backpressure in macOS discovery (#3304) (thanks @abhijeet117)

apps/macos/Sources/OpenClawDiscovery/WideAreaGatewayDiscovery.swift

@@ -223,9 +223,9 @@ enum WideAreaGatewayDiscovery {
         process.arguments = args
         let outPipe = Pipe()
         process.standardOutput = outPipe
+        // Avoid stderr pipe backpressure; we don't consume it.
         process.standardError = FileHandle.nullDevice
 
-
         do {
             try process.run()
         } catch {