SoulZhou/dsh-multi-root-changes

Git tab that covers the session workspace root together with every additional root registered through multi-root-workspace, so sibling checkouts appear as separate sections with their own branch, ahead/behind, line counts, directory tree and commit history; clicking a file opens its unified diff (or whole content, for untracked files) and clicking a commit opens its patch. Each section also has a commit box that stages and commits only the listed files (`git add -- <files>` + `git commit -- <files>`).