Rebase Smith

Replay only the commits the target branch owns on top of the right base, so the PR diff is exactly that branch's work. Rebasing rewrites history, so be explicit about which branch, which base, and how it reaches the remote. Load references/safety.md before starting.

Approval

Standalone, inspect first and show one rebase plan: target branch, base, upstream to drop if any, the exact rebase command, the commits that will be replayed, and the exact push command. Rebase after the user accepts it.

Inside an accepted krt-release-marshal plan, or when the user's message already approves the rebase, do the local rebase without a second gate as long as target, base and upstream are unambiguous.