feat: Add admin settings for dealer comment & domestic cost, enhance visitor country stats

- Add show_dealer_comment toggle to admin settings
- Add domestic_export_customs_krw setting for cost page
- Cost page now uses dynamic settings instead of hardcoded values
- Enhance Visitor Stats with dedicated Country Stats card with flags
- Fix hero_banners API route ordering (422 error fix)
- Fix banner toggle logic to check HeroBanner table instead of car.is_banner
- Add country flag emojis for 23+ countries

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

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

backend/app/api/hero_banners.py

@@ -143,6 +143,46 @@ def get_banner_cars(
     }
 
 
+@router.put("/admin/reorder")
+def reorder_banners(
+    request: BannerReorderRequest,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_admin_user)
+):
+    """배너 순서 재정렬 (Admin)
+
+    car_ids: 배너 차량 ID 목록 (원하는 순서대로)
+    """
+    for order, car_id in enumerate(request.car_ids):
+        banner = db.query(HeroBanner).filter(HeroBanner.car_id == car_id).first()
+        if banner:
+            banner.display_order = order
+
+    db.commit()
+    return {"message": "Banner order updated", "count": len(request.car_ids)}
+
+
+@router.put("/admin/settings", response_model=HeroBannerSettingsResponse)
+def update_banner_settings(
+    settings_data: HeroBannerSettingsUpdate,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_admin_user)
+):
+    """배너 슬라이더 설정 수정 (Admin)"""
+    settings_obj = db.query(HeroBannerSettings).first()
+    if not settings_obj:
+        settings_obj = HeroBannerSettings()
+        db.add(settings_obj)
+
+    update_data = settings_data.model_dump(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(settings_obj, field, value)
+
+    db.commit()
+    db.refresh(settings_obj)
+    return settings_obj
+
+
 @router.get("/admin/{banner_id}", response_model=HeroBannerResponse)
 def admin_get_banner(
     banner_id: int,
@@ -218,27 +258,6 @@ def delete_banner(
     return {"message": "Banner deleted successfully"}
 
 
-@router.put("/admin/settings", response_model=HeroBannerSettingsResponse)
-def update_banner_settings(
-    settings_data: HeroBannerSettingsUpdate,
-    db: Session = Depends(get_db),
-    current_user: User = Depends(get_admin_user)
-):
-    """배너 슬라이더 설정 수정 (Admin)"""
-    settings_obj = db.query(HeroBannerSettings).first()
-    if not settings_obj:
-        settings_obj = HeroBannerSettings()
-        db.add(settings_obj)
-
-    update_data = settings_data.model_dump(exclude_unset=True)
-    for field, value in update_data.items():
-        setattr(settings_obj, field, value)
-
-    db.commit()
-    db.refresh(settings_obj)
-    return settings_obj
-
-
 # ==================== Image Upload ====================
 
 @router.post("/admin/upload-image")
@@ -297,18 +316,19 @@ def toggle_banner(
 ):
     """차량의 배너 상태 토글 (Admin)
 
-    - is_banner=False → True: HeroBanner 생성
-    - is_banner=True → False: HeroBanner 삭제
+    - HeroBanner 존재 → 삭제
+    - HeroBanner 없음 → 생성
     """
     car = db.query(Car).filter(Car.id == car_id).first()
     if not car:
         raise HTTPException(status_code=404, detail="Car not found")
 
-    if car.is_banner:
+    # HeroBanner 테이블을 기준으로 판단 (car.is_banner 필드 대신)
+    existing_banner = db.query(HeroBanner).filter(HeroBanner.car_id == car_id).first()
+
+    if existing_banner:
         # 배너에서 제거
-        banner = db.query(HeroBanner).filter(HeroBanner.car_id == car_id).first()
-        if banner:
-            db.delete(banner)
+        db.delete(existing_banner)
         car.is_banner = False
         db.commit()
         return {"car_id": car_id, "is_banner": False, "message": "Removed from banner"}
@@ -341,22 +361,3 @@ def toggle_banner(
         db.commit()
         db.refresh(banner)
         return {"car_id": car_id, "is_banner": True, "banner_id": banner.id, "message": "Added to banner"}
-
-
-@router.put("/admin/reorder")
-def reorder_banners(
-    request: BannerReorderRequest,
-    db: Session = Depends(get_db),
-    current_user: User = Depends(get_admin_user)
-):
-    """배너 순서 재정렬 (Admin)
-
-    car_ids: 배너 차량 ID 목록 (원하는 순서대로)
-    """
-    for order, car_id in enumerate(request.car_ids):
-        banner = db.query(HeroBanner).filter(HeroBanner.car_id == car_id).first()
-        if banner:
-            banner.display_order = order
-
-    db.commit()
-    return {"message": "Banner order updated", "count": len(request.car_ids)}