.env.example

```
# Server Configuration
PORT=3001
NODE_ENV=development

# MongoDB Configuration
MONGODB_URI=mongodb://localhost:27017/pencere-hesaplama

# JWT Secret
JWT_SECRET=your-super-secret-jwt-key-change-this-in-production

# Optional: MongoDB Atlas Cloud Database
# MONGODB_URI=mongodb+srv://username:password@cluster.mongodb.net/pencere-hesaplama?retryWrites=true&w=majority
```