Session handoff & context management for DeepSeek Harness.
- Handoff: handoff_status / handoff_export (structured Markdown + handoff package) / handoff_resume
- ACP: acp_status / acp_compress / acp_decompress / acp_search / acp_config / acp_set_limit
- Session management: session_list / session_trash / session_restore / session_purge
- Model routes: model_routes / model_switch (same model across vendors/plans)
- 25 unit tests; verified clean boot