Fermi generator can be shut down gracefully

[git-union-dev]

Description

As a user, I want to be able to trigger a graceful shutdown of the fermi generator to minimize potential risks during maintenance or emergencies.

Acceptance criteria

• User is granted access to the fermi generator controls
• User triggers the shutdown process
• Fermi generator power output gradually reduces to zero
• All safety mechanisms remain active during the shutdown process
• System validates and logs the successful shutdown