feat: Add car availability check feature

- Add daily scheduled check for Carmodoo car availability
- Add manual trigger button in admin settings
- Mark sold cars as soldout=True automatically
- Add settings for check time and enable/disable toggle
- Display check status and statistics in admin UI

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

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

backend/app/api/settings.py

@@ -1,4 +1,4 @@
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends, HTTPException, BackgroundTasks
 from sqlalchemy.orm import Session
 
 from ..database import get_db
@@ -6,6 +6,7 @@ from ..models.settings import SystemSettings
 from ..schemas.settings import SystemSettingsUpdate, SystemSettingsResponse
 from .auth import get_current_user
 from ..models import User
+from ..services.car_availability_service import run_car_availability_check
 
 router = APIRouter(prefix="/settings", tags=["settings"])
 
@@ -71,3 +72,57 @@ def update_system_settings(
     db.commit()
     db.refresh(settings)
     return settings
+
+
+# ==================== Car Availability Check Endpoints ====================
+
+@router.post("/car-availability-check")
+async def trigger_car_availability_check(
+    background_tasks: BackgroundTasks,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_admin_user)
+):
+    """차량 판매상태 검증 즉시 실행 (Admin)"""
+    # 백그라운드에서 실행
+    async def run_check():
+        from ..database import SessionLocal
+        check_db = SessionLocal()
+        try:
+            await run_car_availability_check(check_db)
+        finally:
+            check_db.close()
+
+    import asyncio
+    asyncio.create_task(run_check())
+
+    return {
+        "message": "Car availability check started in background",
+        "status": "running"
+    }
+
+
+@router.get("/car-availability-status")
+def get_car_availability_status(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_admin_user)
+):
+    """차량 판매상태 검증 상태 조회 (Admin)"""
+    settings = get_or_create_settings(db)
+
+    # soldout 통계
+    from ..models.car import Car
+    total_cars = db.query(Car).filter(Car.source == 'carmodoo').count()
+    available_cars = db.query(Car).filter(Car.source == 'carmodoo', Car.soldout == False).count()
+    sold_cars = db.query(Car).filter(Car.source == 'carmodoo', Car.soldout == True).count()
+
+    return {
+        "check_enabled": settings.car_availability_check_enabled,
+        "check_hour": settings.car_availability_check_hour,
+        "last_check": settings.car_availability_last_check,
+        "last_result": settings.car_availability_last_result,
+        "stats": {
+            "total_cars": total_cars,
+            "available": available_cars,
+            "sold": sold_cars
+        }
+    }