detailsFromContext missing issue guard

Trap: dereferencing parsePublishTitle(title).groups looks concise because workflow issue contexts normally include a valid publish title, but manual or unexpected contexts yield an opaque TypeError. Fix: detailsFromContext() must explicitly reject absent issue context and malformed titles before accessing groups, using actionable errors. Chose explicit validation over implicit dereference because callers need fail-closed, diagnosable rejection of invalid publish requests.