DeepSeek Harness chat history and session management: search archives, restore conversations, and delete safely

DeepSeek Harness session manager: delete, archive, move across workspaces, migrate presets, favorites, review-later, search, filter, sort, priority, tags, notes, and batch actions. | DSH 会话管理：删除、归档、跨工作区移动、预设迁移、收藏、待回看、搜索、筛选、排序、优先级、标签、备注及批量操作。