feat: Add banner toggle and soldout tracking to Cars page

- Add is_banner, soldout fields to Car model
- Add banner toggle API (POST /hero-banners/admin/toggle/{car_id})
- Add soldout APIs (POST/DELETE /cars/{car_id}/soldout)
- Add nightly soldout checker in agent (runs at 3:00 AM)
- Update Local Cars UI with banner checkbox and status column
- Remove hero-banners admin page (functionality moved to Cars page)
- Banner cars sorted to top with purple background
- Soldout cars displayed with gray overlay

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/soldout_service.py

@@ -0,0 +1,121 @@
+"""
+Soldout Check Service - Checks if cars are still available on Carmodoo
+"""
+
+import logging
+from datetime import datetime
+from typing import List, Tuple
+from sqlalchemy.orm import Session
+import httpx
+
+from ..models.car import Car
+
+logger = logging.getLogger(__name__)
+
+
+class SoldoutChecker:
+    """Carmodoo에서 차량 판매 여부를 확인하는 서비스"""
+
+    def __init__(self, db: Session, carmodoo_session_cookie: str = None):
+        self.db = db
+        self.carmodoo_session_cookie = carmodoo_session_cookie
+        self.carmodoo_base_url = "https://dealer.carmodoo.com"
+
+    async def check_car_availability(self, source_id: str) -> bool:
+        """
+        Carmodoo에서 차량이 아직 판매 중인지 확인
+
+        Returns:
+            True if car is still available, False if sold/removed
+        """
+        try:
+            async with httpx.AsyncClient(timeout=30.0) as client:
+                # Carmodoo 차량 상세 페이지 접근
+                url = f"{self.carmodoo_base_url}/car/carPopView.html"
+                params = {"carNo": source_id}
+
+                headers = {}
+                if self.carmodoo_session_cookie:
+                    headers["Cookie"] = self.carmodoo_session_cookie
+
+                response = await client.get(url, params=params, headers=headers)
+
+                if response.status_code == 404:
+                    return False
+
+                # 페이지 내용에서 "판매완료", "삭제", "없는 차량" 등 확인
+                content = response.text.lower()
+                sold_keywords = [
+                    "판매완료", "판매 완료", "sold", "삭제된", "없는 차량",
+                    "존재하지 않", "찾을 수 없", "not found"
+                ]
+
+                for keyword in sold_keywords:
+                    if keyword in content:
+                        return False
+
+                return True
+
+        except Exception as e:
+            logger.error(f"Error checking car {source_id}: {e}")
+            # 에러 발생 시 available로 간주 (안전하게)
+            return True
+
+    async def check_all_cars(self) -> Tuple[int, int, List[int]]:
+        """
+        모든 활성 차량의 판매 여부 확인
+
+        Returns:
+            (checked_count, soldout_count, soldout_car_ids)
+        """
+        # soldout=False인 활성 차량만 조회
+        cars = self.db.query(Car).filter(
+            Car.status == "active",
+            Car.soldout == False,
+            Car.source == "carmodoo"
+        ).all()
+
+        logger.info(f"Checking {len(cars)} cars for soldout status...")
+
+        checked = 0
+        soldout_count = 0
+        soldout_ids = []
+
+        for car in cars:
+            is_available = await self.check_car_availability(car.source_id)
+            checked += 1
+
+            if not is_available:
+                car.soldout = True
+                soldout_count += 1
+                soldout_ids.append(car.id)
+                logger.info(f"Car {car.id} ({car.car_name}) marked as SOLD OUT")
+
+            # Rate limiting
+            if checked % 10 == 0:
+                logger.info(f"Progress: {checked}/{len(cars)} checked, {soldout_count} sold out")
+                import asyncio
+                await asyncio.sleep(1)
+
+        self.db.commit()
+
+        logger.info(f"Soldout check completed: {checked} checked, {soldout_count} sold out")
+        return checked, soldout_count, soldout_ids
+
+    def mark_soldout(self, car_id: int) -> bool:
+        """수동으로 차량을 soldout 처리"""
+        car = self.db.query(Car).filter(Car.id == car_id).first()
+        if car:
+            car.soldout = True
+            self.db.commit()
+            return True
+        return False
+
+    def mark_available(self, car_id: int) -> bool:
+        """수동으로 차량을 available 처리"""
+        car = self.db.query(Car).filter(Car.id == car_id).first()
+        if car:
+            car.soldout = False
+            self.db.commit()
+            return True
+        return False