@dsh/plugin-manager: DSH Plugin Manifest and Transactional Profile Manager

DeepSeek Harness (DSH) introduces a new plugin management tool, `@dsh/plugin-manager`, serving as the control plane for Profile transactions. Independent of the legacy `component-hub`, it focuses on plugin lifecycle management. Core features include: plugin source and status classification; seven built-in conflict detection mechanisms; standard transaction handling (snapshot validation and rollback); hierarchical validation (syntax, configuration, and Loader); and task persistence. It also supports offline import, one-click installation, and CLI interaction. Note that official core plugins are protected and cannot be updated.