Update the cleanup process in vast_start.py to require the user to press ENTER before destroying the instance. This change prevents immediate automatic termination after the subprocess ends, giving the user control over when to tear down the environment.
- Update shebang to use `#!/usr/bin/env python3`.
- Add module docstrings and type hinting across all functions.
- Move configuration variables into clearly defined uppercase constants.
- Improve error handling for file loading and API requests.
- Restructure instance creation and SSH management logic into modular, readable functions.
These changes make the script more robust, easier to maintain, and self-documenting.
