dsh-session-hub: Unifying Remote DSH Sessions and Local Tool History in One Session Tree

dsh-session-hub is a plugin for DSH web designed to address the issue that historical conversations between remote DSH sessions and local tools such as Codex CLI and Claude Code cannot be displayed in a unified session tree. The plugin merges data through the `/api` data layer, supporting remote session aggregation, local history import, SSH tunnel hosting, and incremental synchronization of model configuration, while preserving the functionality of the official sidebar and conversation area. It allows users to view multi-machine history, real-time streaming, and approval cards, and supports sending, canceling, and renaming sessions. Imported local conversations are read-only by default and become editable only after being converted into real DSH sessions, with the source logs remaining unchanged. The plugin provides independent feature toggles and is simple to install, requiring only the `dsh plugin` command to add it. The environment requires Node 22+ and is applicable solely to the web p