dsh-git-graph: Git Commit Graph and Working Tree View Plugin

`dsh-git-graph` is a Git visualization plugin developed for DeepSeek Harness under the MIT License. The plugin provides a visual commit graph view in the browser sidebar, displaying lanes, branches, and merge activity, while also supporting a worktree list view. Agents can query history using the `git_graph` and `git_worktree` tools. The plugin runs in read-only mode to ensure safety and supports configuring history depth and access paths. It is suitable for scenarios that require analyzing repository topology and branch management.