feat(web,mobile): jj terminology and shared vcs action logic

[THEjacob1000]

What Changed

Web and mobile say change, bookmark and workspace when the thread's repo is jj. One useVcsTerminology hook per client reads vcs.kind and the shared action logic in client-runtime takes the terminology as input, so the copy lives in one place. Adds an Initialize Jujutsu button beside Initialize Git, a remove-workspace action on mobile, and the internals and user docs.

Why

Without this the UI tells a jj user to check out a branch in a repo that has none. Git path is wording only, no behaviour change there.

Stack

1. feat(vcs): jj driver, detection and process wrapper #11373
2. feat(server): jj-native checkpoints and review diffs #11382
3. feat(server): route workflow, hosting glue, and discovery by vcs kind #11383
4. This PR

GitHub can't create stacked PRs from a fork, so the diff carries the PRs below. Review the top commit only.

UI Changes

Manually exercised in the installed Linux desktop app, build 2a249f8e503a (the complete stack), using disposable repositories. These captures verify the integrated stack, not each lower PR in isolation.

Captured Initialize Jujutsu before/after, bookmark creation, a new workspace, the no-Git-hooks commit dialog, selected-file commit and both review scopes. A plain Git fixture still says branches/current checkout, and unsupported jj displays its disabled-action explanation.

Mobile and remote action states remain untested. Workspace details were rechecked in an isolated dev instance.

Initialization before and after

01-initialize-jj.mp4

Git and jj terminology comparison

Workspace and selected-file commit recordings

03-workspace.mp4

04-selected-file-commit.mp4

Workspace details before and after

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

Evidence captured with Codex; test turns used GPT-6 Astra.

[t3dotgg]

Note

🤖 GPT-6 Astra responding on behalf of Theo

We're closing this as part of a cleanup of old PRs. Thank you for the time and care you put into this contribution.

The current comparison includes 1,530 files and 488,810 changed lines, with conflicts in 566 files against the target branch. Much of that comparison comes from diverged base history, beyond the change described here. The latest implementation commit is from 2026-09-20.

At this point, regenerating a focused patch against the current intended base would be easier to review and maintain than updating this PR. We appreciate the problem report and the work already done; this thread will remain available as a reference. If you revisit it, please confirm the current direction with us and link a fresh, focused PR back here.