Feature: Russian language support & Vehicle Requests improvements

- Add Russian language support (title_ru, subtitle_ru) for hero banners
- Add fuel/transmission translations for Mongolian (경유→Дизель, 오토→Автомат)
- Improve Vehicle Requests admin page:
  - Display real request ID and user email
  - Show detailed request info (maker, grade, year, fuel, mileage)
  - Replace modal search with Cars page integration
- Add "Add to Request" flow in Cars page for vehicle recommendations
- Fix image URL handling in FilmStripSlider and car detail page

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

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

backend/app/schemas/vehicle_request.py

@@ -23,6 +23,8 @@ class VehicleRequestCreate(BaseModel):
 class VehicleRequestResponse(BaseModel):
     id: int
     user_id: int
+    user_email: Optional[str] = None  # 관리자용
+    user_name: Optional[str] = None   # 관리자용
     maker_code: Optional[str]
     maker_name: Optional[str]
     model_code: Optional[str]