dsh-session-kit: Enhancing DeepSeek Harness Session Management via Official Extension Points

`dsh-session-kit` is a DeepSeek Harness plugin maintained by ltxlong (v1.1.0, MIT license). It does not modify the DSH core source code but enhances the routine management capabilities of the session page via official extension points, allowing for a clean rollback after plugin uninstallation. After installation, a "Session Management" button appears in the header of the session page, supporting session deletion (protected while running, moved to system Recycle Bin), renaming, forking, archiving, opening directory, exporting, and tool call statistics. Archived sessions can be searched by title, previewed in a popup, forked, restored, or deleted. For completed turns, the plugin provides "Delete this turn and all subsequent" and "Regenerate" operations. It adopts a conservative strategy of appending persistent tombstones instead of wiping logs, after obtaining an Agent maintenance lease and verifying turn safety.