fix(bridge): 0x7E iZotope — append core DLL dirs (Program Files/iZotope/*/Cores) vao PATH truoc Module::create

iZotope VST3 single-file (Ozone 11.vst3) reference core DLL
(iZOzone11Core.dll) dat rieng o C:\Program Files\iZotope\<Product>\Cores,
khong canh .vst3. SetDllDirectoryW chi phu dir canh plugin -> LoadLibraryW
fail ERROR_MOD_NOT_FOUND (0x7E) -> Windows dialog khi app load plugin.
VstDllSearch.h quet cac dir Cores co dinh + append vao PATH (process-global,
bridge load 1 plugin 1 luc). Ap dung ca RenderFxJob (FX chain + scan) va
Vst3Instrument (VSTi).

native_bridge/include/VstDllSearch.h

@@ -0,0 +1,71 @@
+// native_bridge/include/VstDllSearch.h
+// iZotope VST3 (Ozone 11, Nectar, Neutron...) là single-file .vst3 — core
+// DLL (vd iZOzone11Core.dll) nằm RIÊNG ở
+//   C:\Program Files\iZotope\<Product>\Cores
+// KHÔNG cạnh plugin → LoadLibraryW của VST3 SDK fail ERROR_MOD_NOT_FOUND
+// (0x7E) dù setPluginSearchPath đã trỏ dir cạnh plugin. Helper này quét các
+// dir Cores cố định và thêm vào PATH (process-global — bridge load 1 plugin
+// 1 lúc, giống SetDllDirectoryW hiện có).
+#ifndef VST_DLL_SEARCH_H
+#define VST_DLL_SEARCH_H
+
+#include <string>
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#ifdef _WIN32
+inline std::string vstDllSearchExtras() {
+    std::string extras;
+    const char* bases[] = {
+        "C:\\Program Files\\iZotope",
+        "C:\\Program Files\\Common Files\\iZotope",
+    };
+    for (const char* base : bases) {
+        std::string pat = std::string(base) + "\\*";
+        WIN32_FIND_DATAA fd;
+        HANDLE h = FindFirstFileA(pat.c_str(), &fd);
+        if (h == INVALID_HANDLE_VALUE) continue;
+        do {
+            if (!(fd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) continue;
+            if (fd.cFileName[0] == '.') continue;
+            std::string cores = std::string(base) + "\\" + fd.cFileName + "\\Cores";
+            if (GetFileAttributesA(cores.c_str()) != INVALID_FILE_ATTRIBUTES) {
+                if (!extras.empty()) extras += ";";
+                extras += cores;
+            }
+        } while (FindNextFileA(h, &fd));
+        FindClose(h);
+    }
+    return extras;
+}
+
+// Append extras vào PATH (bỏ dir đã có). Gọi TRƯỚC Module::create.
+inline void vstAddDllSearchPath(const std::string& extras) {
+    if (extras.empty()) return;
+    char buf[32768];
+    DWORD n = GetEnvironmentVariableA("PATH", buf, sizeof(buf));
+    std::string path = n ? std::string(buf) : "";
+    std::string toAdd;
+    size_t start = 0;
+    while (start <= extras.size()) {
+        size_t end = extras.find(';', start);
+        std::string dir = extras.substr(start, end == std::string::npos ? std::string::npos : end - start);
+        if (!dir.empty() && path.find(dir) == std::string::npos) {
+            if (!toAdd.empty()) toAdd += ";";
+            toAdd += dir;
+        }
+        if (end == std::string::npos) break;
+        start = end + 1;
+    }
+    if (toAdd.empty()) return;
+    if (!path.empty()) path += ";";
+    path += toAdd;
+    SetEnvironmentVariableA("PATH", path.c_str());
+}
+#else
+inline std::string vstDllSearchExtras() { return std::string(); }
+inline void vstAddDllSearchPath(const std::string&) {}
+#endif
+
+#endif // VST_DLL_SEARCH_H

native_bridge/src/RenderFxJob.cpp

@@ -10,6 +10,7 @@
 // MIDI/GUI — component + controller, audio buses, processData with input
 // buffers copied directly (setChannelBuffers is unusable: prepare() owns them).
 #include "RenderFxJob.h"
+#include "VstDllSearch.h"
 
 // sheredom/json.h (public domain) — vendored copy; SDK copy as fallback.
 #if __has_include("sheredom_json.h")
@@ -443,6 +444,10 @@ static void setPluginSearchPath(const std::string& path) {
     // at a time (render slots serial; realtime chain loads on its own thread).
     std::wstring wdir(dir.begin(), dir.end());
     SetDllDirectoryW(wdir.c_str());
+    // iZotope core DLLs sống ở C:\Program Files\iZotope\<Product>\Cores (KHÔNG
+    // cạnh .vst3) — SetDllDirectoryW chỉ phủ dir cạnh plugin, core vẫn 0x7E.
+    // Append Cores dirs vào PATH (LoadLibraryW search PATH sau app/system dirs).
+    vstAddDllSearchPath(vstDllSearchExtras());
     std::cerr << "[RenderFx] dll search dir: " << dir << std::endl;
 }
 #endif

native_bridge/src/Vst3Instrument.cpp

@@ -8,6 +8,7 @@
 // connect them, process MIDI events + audio blocks, and attach the editor
 // view to a native HWND (openGUI) for the floating GUI (B9).
 #include "Vst3Instrument.h"
+#include "VstDllSearch.h"
 
 #ifdef HAVE_VST3SDK
 #ifdef _WIN32
@@ -254,6 +255,11 @@ bool Vst3Instrument::loadPlugin(const std::string& path, double sampleRate) {
     using namespace VST3::Hosting;
 
     std::string err;
+#ifdef _WIN32
+    // iZotope VST3 core DLLs (vd iZOzone11Core.dll) nằm ở
+    // C:\Program Files\iZotope\<Product>\Cores — không cạnh .vst3, cần PATH.
+    vstAddDllSearchPath(vstDllSearchExtras());
+#endif
     Module::Ptr module = Module::create(path, err);
     if (!module) {
         std::cerr << "[Vst3Instrument] Module::create failed: " << err << std::endl;