Function compute_urgency 

pub fn compute_urgency(s: &UrgencySignals) -> f32

Score a candidate’s urgency for the floor (ADR-062 D4 + ADR-068 ERL term).

base    = 0.30·semantic + 0.15·arousal + 0.20·wait + 0.10·crowd + 0.25·readiness
urgency = base · erl_scale            ; erl_scale = erl.clamp(0,1) or 1.0 if None
        ; hard interrupt ⇒ f32::MAX