fix: banner translations and deployment improvements

- Add translateCarName import from i18n.ts for proper multilingual support
- Change default API language from 'ko' to 'en' for hero banners
- Add checkbox column for Local Cars banner registration
- Update Dockerfile with Playwright dependencies
- Add PostgreSQL migration script
- Add banner translation fix script

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

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

backend/app/main.py

@@ -1,6 +1,8 @@
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
+from starlette.middleware.base import BaseHTTPMiddleware
+from starlette.responses import RedirectResponse
 from contextlib import asynccontextmanager
 import os
 import asyncio
@@ -15,6 +17,42 @@ from datetime import datetime, timedelta
 
 app_settings = get_settings()
 
+
+class TrailingSlashMiddleware(BaseHTTPMiddleware):
+    """
+    Middleware to normalize trailing slashes on API paths.
+    Uses redirect to strip trailing slashes from non-root routes.
+
+    Routes defined with "/" (like /hero-banners/) keep trailing slash.
+    Routes defined without "/" (like /cars) get redirected.
+    """
+    # Routes that are defined WITH trailing slash (router.get("/"))
+    TRAILING_SLASH_ROUTES = {
+        "/api/hero-banners/",
+        "/api/settings/",
+        "/api/notifications/",
+        "/api/vehicle-requests/",
+    }
+
+    async def dispatch(self, request: Request, call_next):
+        path = request.url.path
+
+        # Skip if it's a known trailing-slash route
+        if path in self.TRAILING_SLASH_ROUTES:
+            return await call_next(request)
+
+        # Redirect trailing slash from other /api/* paths
+        if path.startswith("/api/") and path.endswith("/") and len(path) > 5:
+            new_path = path.rstrip("/")
+            if request.url.query:
+                new_url = f"{new_path}?{request.url.query}"
+            else:
+                new_url = new_path
+            return RedirectResponse(url=new_url, status_code=307)
+
+        return await call_next(request)
+
+
 # Create tables
 Base.metadata.create_all(bind=engine)
 
@@ -118,6 +156,9 @@ app = FastAPI(
     lifespan=lifespan
 )
 
+# Trailing slash middleware (must be added before CORS)
+app.add_middleware(TrailingSlashMiddleware)
+
 # CORS - credentials=True requires explicit origins (not "*")
 app.add_middleware(
     CORSMiddleware,
@@ -126,6 +167,8 @@ app.add_middleware(
         "http://127.0.0.1:3000",
         "http://localhost:8000",
         "http://192.168.0.202:3000",  # Local network
+        "https://autonetsellcar.com",  # Production
+        "http://autonetsellcar.com",   # Production (HTTP redirect)
     ],
     allow_credentials=True,
     allow_methods=["*"],