Out-of-process rebuild: Add Helper/HelperIPC.h/.cpp — Unix socket IPC listener

Source/Helper/HelperIPC.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <juce_core/juce_core.h>
+#include <thread>
+#include <atomic>
+#include <functional>
+
+class HelperPluginHost;
+
+class HelperIPC
+{
+public:
+    HelperIPC(int parentPid, HelperPluginHost& host);
+    ~HelperIPC();
+
+    bool connect();
+    void disconnect();
+
+    void sendReady();
+    void sendParamChanged(int index, float value);
+
+private:
+    void listenLoop();
+    void handleMessage(const juce::String& message);
+    void sendMessage(const juce::String& json);
+
+    int parentPid;
+    HelperPluginHost& host;
+
+    int socketFd = -1;
+    std::thread listenThread;
+    std::atomic<bool> running{false};
+};