FIX: sửa lỗi không load instrument của soundfont trên window

app/core/render_engine.py

@@ -35,6 +35,21 @@ def _find_sf2_path(sf_id: str) -> str:
             fbase, fext = os.path.splitext(fname)
             if fext.lower() in (".sf2", ".sf3") and (fbase.lower() == clean_lower or fbase.lower() == sf_lower):
                 return os.path.join(base_dir, fname)
+    # Thư mục user thêm qua Plugin Manager (plugin_dirs — Add Directory):
+    # soundfont trong thư mục user phải render được (Windows thường dùng cách này)
+    try:
+        from app.core.vst_engine import _load_user_plugin_dirs
+        for base_dir in _load_user_plugin_dirs():
+            if not os.path.isdir(base_dir):
+                continue
+            for root, dirs, files in os.walk(base_dir):
+                for fname in files:
+                    fbase, fext = os.path.splitext(fname)
+                    if fext.lower() in (".sf2", ".sf3") and (fbase.lower() == clean_lower or fbase.lower() == sf_lower):
+                        return os.path.join(root, fname)
+                dirs[:] = []  # không walk sâu
+    except Exception:
+        pass
     static_dir = os.path.join(settings.APP_DIR, "static", "soundfonts")
     if os.path.isdir(static_dir):
         for fname in os.listdir(static_dir):