Jujutsu-safe exact-change PR workflow

In .jj/ workspaces, use non-interactive jj for mutations and stable change IDs. Identify the intended nonempty change explicitly; an empty child often makes @ wrong. Inspect its diff, description, parent, bookmark, and conflicts before proceeding. Rebase onto current upstream, then verify jj st, jj log, and exact file scope because conflicts are recorded without necessarily failing commands. Never rewrite immutable commits; recover mistakes with jj undo or jj op restore. Create or identify the change’s bookmark, push only it, and stop on push or branch-detection failure. Open the PR against the repository default branch with assignee @me, ## Summary, and concise impact-focused changes. Validate and review the exact pushed head; confirm the PR contains only the intended change and all required checks pass.