fix(bridge): VST2 host dung ABI SDK — crash outs>2, NaN input, editOpen(NULL), opcodes; docs A14 MIDI-out + phan tich Ozone -Inf

- aeffect.h: bo sung opcodes 4-22, 53, 55 + audioMaster 15/41-44 + ERect (dung chuan VST2.4 SDK, DUNE load OK khong crash)
- Vst2Instrument: cap du pointer arrays theo numInputs/numOutputs (fix AV 0xC0000005 Qin outs=32), input fill 0.0f (het NaN poison effect), bo probe effEditOpen(NULL) (crash WaveObserver), GetDirectory + SizeWindow hook, canDo sendVstEvents/sendVstTimeInfo
- TASKS.md: A14 MIDI-out tu plugin (Scaler2/Instacomposer/MelodicFlow xuat MIDI khong phai audio)
- PLAN_MASTERBUS_FX_RACK_VST.md: phan tich Ozone -Inf — chain day du, nguyen nhan = audio DAW khong chay qua bridge master ring

native_bridge/src/Vst2Instrument.h

@@ -1,8 +1,9 @@
 // native_bridge/src/Vst2Instrument.h
 // VST2 (VST 2.4, 64-bit) instrument host. Clean-room ABI header
 // (native_bridge/vestige/aeffect.h) — no Steinberg SDK, no LMMS code.
-// Headless: no GUI editor (openGUI returns false); preset state is kept via
-// effGetChunk/effSetChunk (fxp-style chunks).
+// GUI editor: supported for plugins with kEffectFlagsHasEditor (effEditOpen/
+// effEditClose/effEditIdle); preset state is kept via effGetChunk/effSetChunk
+// (fxp-style chunks).
 #ifndef VST2_INSTRUMENT_H
 #define VST2_INSTRUMENT_H
 
@@ -27,9 +28,11 @@ public:
     void programChange(uint32_t channel, uint32_t program) override;
     void pitchBend(uint32_t channel, uint32_t bend14) override;
     bool openGUI(void* parentWindowHandle) override;
-    bool canOpenGUI() const override { return false; }
+    bool canOpenGUI() const override;
+    bool attachView(void* parentWindowHandle) override;
     void closeGUI() override;
     bool hasAttachedView() const override;
+    void guiIdle() override;
     void captureState() override;
     void restoreState() override;
     std::string serializeState() const override;
@@ -39,19 +42,31 @@ public:
     // Accessors used by the audioMaster callback (same translation unit's
     // friend-ish helpers) without exposing AEffect* in the header.
     double sampleRate() const { return sampleRate_; }
+    const std::string& pluginDir() const { return pluginDir_; }
     uint32_t maxBlockSize() const { return maxBlockSize_; }
     const void* effect() const;  // AEffect*; null until loaded
+    // Host window the editor is attached to (attachView sets, closeGUI
+    // clears). The audioMaster SizeWindow handler moves it via the hook.
+    void* editorParent() const { return editorParent_; }
+    // Register the SizeWindow hook (main.cpp posts the resize to the UI
+    // worker). Probe builds never set it -> no-op.
+    static void setResizeHook(void (*fn)(void* hwnd, int w, int h));
 
 private:
     void* state_;          // Vst2HostState* (pimpl — aeffect.h stays out of the header)
     std::string path_;
+    std::string pluginDir_;
     double sampleRate_;
     uint32_t maxBlockSize_;
     bool loaded_;
+    bool guiAttached_ = false;   // effEditOpen done, not yet effEditClose'd
+    void* editorParent_ = nullptr;  // host window the editor is a child of
     uint32_t channel_ = 0;
-    // scratch buffers for silent plugin inputs
+    // scratch buffers for silent plugin inputs and extra output channels
+    // (plugins with numOutputs > 2 need full pointer arrays)
     std::vector<float> inL_;
     std::vector<float> inR_;
+    std::vector<float> extraOut_;
 };
 
 #endif // VST2_INSTRUMENT_H