Environment configuration

Where settings come from.

Copy .env.example to .env and fill it in. Never commit real values. Some of the variable names it defines:

• APP_ENV, DEBUG, LOG_LEVEL
• DATABASE_URL, REDIS_URL, CELERY_BROKER_URL
• ALLOWED_ORIGINS, NEXT_PUBLIC_API_URL
• AI_PROVIDER and provider key variables
• RAZORPAY_* for payments
• SMTP_* for email

The full reference is docs/operations/environment-variables.md in the repository.