HildebrandYu/dsh-session-chains

Groups the sessions that hand off to each other into one chain in the DSH sidebar — automatic chain detection from the handoff prompt, per-chain numbering, in-place rename, search, drag and multi-select to re-chain, pinning a chain to the top, archiving chains out of the sidebar into a panel-only archive, a per-session context/steps readout, and configurable handoff thresholds that can trigger an automatic handoff (write the next prompt, open a new session, paste it, switch over).