Reorganized and enhanced the OpenAPI fetch logic for better maintainability and error handling. Key updates include improved environment variable validation, more detailed error messages, streamlined configuration loading, and additional safety checks for file paths and directories. Added proper logging and ensured the process flow is easy to trace.

Reorganized and enhanced the OpenAPI fetch logic for better maintainability and error handling. Key updates include improved environment variable validation, more detailed error messages, streamlined configuration loading, and additional safety checks for file paths and directories. Added proper logging and ensured the process flow is easy to trace.

Simplify and streamline OpenAPI client generation and backend startup logic. Improved error handling, environment configuration, and self-signed SSL certificate management. Added support for generating OpenAPI schema via command-line argument.