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/include/INativeInstrument.h

@@ -55,6 +55,9 @@ public:
     virtual bool reloadForGUI() { return true; }
     virtual bool attachView(void* /*parentWindowHandle*/) { return false; }
     virtual void resizeView(int /*w*/, int /*h*/) {}
+    // Periodic idle tick for attached editors (VST2 effEditIdle repaints;
+    // others: no-op). Called on the UI worker's pump loop.
+    virtual void guiIdle() {}
     // True while the editor view is attached (GUI window open). The bridge uses
     // it to dedupe repeated OPEN_GUI (frontend retry spam) — re-attaching a
     // view that is already attached corrupts plugins (Nexus createView→null).

native_bridge/include/NativeInstrumentEngine.h

@@ -149,6 +149,10 @@ public:
     // Zero L/R then sum each assigned instrument into it.
     void renderAll(float* outputL, float* outputR, uint32_t numSamples);
 
+    // Periodic idle tick for every attached editor (VST2 effEditIdle). Runs
+    // on the UI worker thread's pump loop; no-op for engines without editors.
+    void guiIdleAll();
+
     size_t count() const { std::lock_guard<std::mutex> lock(mu_); return channels_.size(); }
 
     void setBypassed(bool on) { isBypassed_.store(on); }