Function fact_summary 

pub fn fact_summary(fact: &StepFact) -> Option<(Icon, String)>

One-line summary of a StepFact for live-frontend display.

Returns None for facts the live UI shouldn’t surface:

• PromptAnswered: the operator just typed it.
• BackendOperation / AttestationRecorded / MachineInfoRecorded: the surrounding action handler already calls Reporter::log with its own narrative line.
• CeremonyCompleted: the frontend renders a dedicated completion screen with the fingerprint.