fix: Prevent duplicate car creation when adding from All Cars tab

- Backend: Check local_car_id first before creating new car
- Frontend: Pass local_car_id to indicate car already exists in DB

backend/app/api/vehicle_requests.py

@@ -337,10 +337,17 @@ def admin_add_vehicle(
     # Extract car data
     car_data = vehicle_data.car_data
     source_id = str(car_data.get("id", ""))
+    local_car_id = car_data.get("local_car_id")  # Already exists in local DB
 
     # Check if car already exists in cars table
     existing_car = None
-    if source_id:
+
+    # First, check by local_car_id (for cars already in local DB)
+    if local_car_id:
+        existing_car = db.query(Car).filter(Car.id == int(local_car_id)).first()
+
+    # If not found, check by carmodoo source_id
+    if not existing_car and source_id:
         existing_car = db.query(Car).filter(
             Car.source == "carmodoo",
             Car.source_id == source_id
@@ -349,6 +356,8 @@ def admin_add_vehicle(
     car_id = None
     if existing_car:
         car_id = existing_car.id
+        # Ensure local_car_id is in car_data for frontend
+        car_data["local_car_id"] = car_id
     elif source_id:
         # Create new car record from car_data
         new_car = Car(

frontend/src/app/admin/cars/page.tsx

@@ -1121,6 +1121,7 @@ export default function CarsAdminPage() {
             request_id: parseInt(requestId),
             car_data: {
               id: car.id.toString(),
+              local_car_id: car.id,  // 로컬 DB에 이미 있는 차량임을 표시
               car_name: car.car_name,
               maker_name: car.maker?.name,
               model_name: car.model?.name,