fix: 3 bug standalone — soundfont preview/play, Carla bridge play item, realtime sync LAN/Tauri

Bug1: dispatcher CREATE_MIDI_ITEM track_id number vs state string -> String(); play+preview native soundfont verified.
Bug2: Carla play item — chờ OSC ready (poll carla-status, queue nốt khi cold start), chống spawn trùng (carla-status dò port bind, open-in-carla skip khi đã chạy).
Bug3: realtime sync — GET /temp/revision (updated_at+client_id), poll 3s, apply qua deserializeProjectFromSchema; hash-skip autosave + client_id chống ping-pong.

app/api/v1/projects.py

@@ -136,6 +136,7 @@ class SaveProjectRequest(BaseModel):
 
 class SaveTempProjectRequest(BaseModel):
     data_json: str
+    client_id: Optional[str] = None  # client ghi bản này (LAN browser / Tauri UI) — chống ping-pong sync
 
 def get_optional_user(authorization: Optional[str] = Header(None)) -> Optional[dict]:
     if authorization and authorization.startswith("Bearer "):
@@ -172,6 +173,10 @@ async def save_temp_project(req: SaveTempProjectRequest, current_user: Optional[
         os.makedirs(temp_dir, exist_ok=True)
         with open(os.path.join(temp_dir, "autosave.json"), "w", encoding="utf-8") as f:
             json.dump({"user_id": user_id, "updated_at": now, "data_json": validated_data_json}, f, ensure_ascii=False)
+        # Revision sidecar (nhỏ) — realtime sync LAN/Tauri đọc updated_at +
+        # client_id KHÔNG cần parse data_json (có thể MB).
+        with open(os.path.join(temp_dir, f"revision_{user_id}.json"), "w", encoding="utf-8") as f:
+            json.dump({"client_id": req.client_id or "", "updated_at": now}, f, ensure_ascii=False)
     except Exception:
         pass
     return {"message": "Đã lưu dự án tạm tự động", "updated_at": now}
@@ -212,6 +217,37 @@ async def get_temp_project(current_user: Optional[dict] = Depends(get_optional_u
         pass
     return {"has_temp": False}
 
+
+@router.get("/temp/revision")
+async def temp_project_revision(current_user: Optional[dict] = Depends(get_optional_user)):
+    """Revision nhẹ của bản temp: updated_at + client_id — frontend poll 2-3s
+    để realtime sync giữa LAN browser và Tauri standalone (không tải full
+    data_json mỗi lần). client_id = client ghi bản cuối → client khác bỏ qua
+    bản do CHÍNH NÓ ghi (chống ping-pong)."""
+    user_id = current_user["user_id"] if current_user else "anonymous"
+    client_id = ""
+    updated_at = 0.0
+    try:
+        from app.config import settings as _st
+        rev_path = os.path.join(_st.STORAGE_DIR, "temp", f"revision_{user_id}.json")
+        if os.path.isfile(rev_path):
+            with open(rev_path, "r", encoding="utf-8") as f:
+                meta = json.load(f)
+            client_id = meta.get("client_id", "") or ""
+            updated_at = float(meta.get("updated_at", 0) or 0)
+    except Exception:
+        pass
+    if not updated_at:
+        conn = get_db_connection()
+        cursor = conn.cursor()
+        cursor.execute("SELECT updated_at FROM projects WHERE id = ? AND is_temp = 1", (f"temp_{user_id}",))
+        row = cursor.fetchone()
+        conn.close()
+        if row:
+            updated_at = float(row["updated_at"] or 0)
+    return {"updated_at": updated_at, "client_id": client_id}
+
+
 def _os_projects_dir() -> str:
     """Thư mục dự án trên hệ điều hành (Ctrl-S desktop):
     Windows → Documents/SonicForgeDAW/Projects (fallback USERPROFILE);