Closes#10961, Closes OPEN-2715
Documents all environment variables that must be configured when deploying
AutoGPT to a new server:
- Quick reference table of critical URLs that must change
- Configuration file locations and loading order
- Security keys that must be regenerated (with generation commands)
- Database, Redis, RabbitMQ configuration
- Default ports for all services
- OAuth callback URLs for all supported providers
- Full deployment checklist
- Docker vs external services guidance
