refactor: Remove unused DB translation system

Static dictionary (i18n.ts CAR_TRANSLATIONS) already covers all terms.
DB translations table had only 179 entries used as fallback and was
never actually reached. Simplifies useTranslate hook to static-only.
DB table preserved for safety.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -2,7 +2,6 @@ from .car import CarMaker, CarModel, Car, CarImage, CarOption
 from .user import User, CarView, PerformanceCheckView, ChargeHistory, VerificationCode
 from .inquiry import Inquiry, InquiryMessage, InquiryStatus, InquiryCategory
 from .hero_banner import HeroBanner, HeroBannerSettings
-from .translation import Translation
 from .cache import CarCache, CarDetailCache, CacheRequestQueue
 from .settings import SystemSettings
 from .vehicle_request import VehicleRequest, RequestVehicle, PurchasedVehicle
@@ -40,7 +39,6 @@ __all__ = [
     "InquiryCategory",
     "HeroBanner",
     "HeroBannerSettings",
-    "Translation",
     "CarCache",
     "CarDetailCache",
     "CacheRequestQueue",

backend/app/models/translation.py

@@ -1,28 +0,0 @@
-from sqlalchemy import Column, Integer, String, DateTime, Index
-from sqlalchemy.sql import func
-from ..database import Base
-
-
-class Translation(Base):
-    """Translation dictionary for car-related terms"""
-    __tablename__ = "translations"
-
-    id = Column(Integer, primary_key=True, index=True)
-
-    # Source text (Korean)
-    source_text = Column(String(500), nullable=False, index=True)
-
-    # Category: maker, model, fuel, transmission, color, car_name, etc.
-    category = Column(String(50), nullable=False, index=True)
-
-    # Translations
-    text_en = Column(String(500))  # English
-    text_mn = Column(String(500))  # Mongolian
-    text_ru = Column(String(500))  # Russian
-
-    created_at = Column(DateTime, default=func.now())
-    updated_at = Column(DateTime, default=func.now(), onupdate=func.now())
-
-    __table_args__ = (
-        Index('ix_translations_source_category', 'source_text', 'category', unique=True),
-    )