v2.9.0

2.9.0 - Adopt dsh rc.8 features: sub-agent backend selection (subagentProvider/subagentModel for agent() calls), interruption awareness and recovery (checkpoint resumeCount, IterationStatus interrupted/resumeCount, dashboard resume chips), image attachment integration (iterate_context relays attached image metadata, parse.js deep-scan helpers, dashboard attachment chips), and a new 'resume' decision-log entry type.