hermes setup hung indefinitely on headless SSH sessions, Docker
containers, and CI/CD environments because the interactive provider
selection menu could not receive input.
Two-layer fix:
1. sys.stdin.isatty() check — auto-detects non-interactive environments
2. --non-interactive flag support — already in CLI parser, now honored
In both cases the wizard exits immediately with helpful guidance
pointing users to 'hermes config set' commands.
Closes#905
