Initial commit: AutonetSellCar platform with deployment system

- Frontend: Next.js 14 with TypeScript
- Backend: FastAPI with SQLAlchemy
- Agent: Carmodoo sync agent
- Deployment: Docker Compose based staging/production setup
- Scripts: Automated deployment with rollback support

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

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

backend/app/database.py

@@ -0,0 +1,27 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from .config import get_settings
+
+settings = get_settings()
+
+# SQLite needs check_same_thread=False for FastAPI
+if settings.USE_SQLITE:
+    engine = create_engine(
+        settings.DATABASE_URL,
+        connect_args={"check_same_thread": False}
+    )
+else:
+    engine = create_engine(settings.DATABASE_URL)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()