RecomputeMbomChangeOrderLineDiffs

Restate the named lines’ diffs against the world now. The button behind the drift banner, scoped to whichever lines the caller names. Nothing else restates: apply refuses on drift, and returning to draft or reopening leaves every diff row as it is, so the author decides when the set moves. Draft only. Under review or approved, return the change order to draft first; canceled or completed, reopen it first.