Function decode_request_reason 

pub fn decode_request_reason(payload: &[u8]) -> String

Extract the override reason an approval_request carried.

Non-empty only for the lethal-trifecta / Rule-of-Two containment override; empty/absent → "" (an ordinary gated call, or a record written before the field existed). Used by the edge to render the gate’s explanation and by forensics to show why a trifecta-gated call was paused.