feat: native host bridge integration — C++ bridge, Rust SHM, JS routing, build scripts, docs

- native_bridge/: InstrumentEngineManager multi-channel, sample-accurate, CC/program/pitchbend, transport, Vst3Instrument stub (HAVE_VST3SDK)
- src-tauri: shm.rs, bridge spawn + audio pump + health monitor, open_vst_gui, externalBin, commands
- app: UnifiedMidiRouter, NativeBridgeService, bridgeAudioNode, audioRoutingEngine, Plugin Manager UI, Bridge/WASM indicator, set_position sync
- build: 3 ps1 (force-added, build/ ignored), verify_bundle --check-bridge, CI workflow
- docs: TASKS.md, TEST_NOTES.md (Windows verify checklist), install/report updates

app/core/vst_engine.py

@@ -551,6 +551,36 @@ def resolve_preset_path(preset_id_or_path: str) -> str:
     return ""
 
 
+def resolve_plugin_path(name_or_path: str, ext: str = "") -> str:
+    """E3: resolve path thật của plugin/soundfont cho Native Bridge (E2).
+    ext: '.vst3' | '.vst2' | '.sf2' | '.sf3' | '.sfz' — filter phần mở rộng
+    khi quét plugin_dirs. Trả '' nếu không tìm thấy. Chống path traversal:
+    chỉ tên file (không separator) hoặc path tồn tại được chấp nhận."""
+    if not name_or_path:
+        return ""
+    p = name_or_path
+    if os.path.isfile(p):
+        return p
+    base = os.path.basename(p.replace("\\", "/"))
+    base_noext = os.path.splitext(base)[0].lower()
+    want_ext = ext.lower() if ext else None
+    dirs = []
+    try:
+        dirs = list(_load_user_plugin_dirs()) or []
+    except Exception:
+        pass
+    dirs += [settings.VST_DIR, settings.SOUNDFONT_DIR]
+    for base_dir in dirs:
+        if not os.path.isdir(base_dir):
+            continue
+        for root, _, files in os.walk(base_dir):
+            for fn in files:
+                if want_ext and not fn.lower().endswith(want_ext):
+                    continue
+                if fn.lower() == base.lower() or os.path.splitext(fn)[0].lower() == base_noext:
+                    return os.path.join(root, fn)
+    return ""
+
 def apply_preset_to_plugin(plugin, preset_id=None, preset_path=None, preset_data_b64=None) -> bool:
     """Gán preset lên plugin pedalboard: bytes nhúng (base64 .vstpreset) ưu
     tiên, sau đó preset_id (thư viện), sau preset_path (file). Trả True nếu