Rebase onto a moving dependency branch without invalidating an in-flight review

When feature B is under independent review on top of dependency A's old tip, and A then moves (fixes from its own review), don't rebase B in place. Create a new branch and worktree (B-r2) on A's new tip, leaving B's reviewed SHA untouched, so the reviewer's diff range (oldA..B) and the compile result stay valid. Compile and test B-r2 in parallel, then apply the review findings to B-r2. Pass reviewers a commit range from the dependency tip (git log A..B), not from an older base, which would mix in the dependency's commits. Also, when an agent reports a SHA, resolve it from the branch (git rev-parse): sub-agent messages sometimes contain truncated or wrong hashes.