Add Railway deployment configuration

- Add Dockerfiles for backend (FastAPI) and frontend (nginx)
- Add railway.toml configs with health checks
- Add .dockerignore files for optimized builds
- Update config.py to auto-convert Railway DATABASE_URL format
- Add FRONTEND_URL env var for production CORS

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

backend/app/main.py

@@ -44,7 +44,7 @@ app.add_middleware(RequestLoggingMiddleware)
 # Configure CORS
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=settings.CORS_ORIGINS,
+    allow_origins=settings.allowed_origins,
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],