becker-charles wants Mike's redlines to land in the right paragraph

Mike's current redline engine locates the spot to edit by matching a snippet of text plus a bit of surrounding context. In documents where similar phrasing repeats - a representations and warranties section, a schedule of definitions, a contract with parallel clauses - that approach can latch onto the wrong paragraph and quietly rewrite the wrong line.

becker-charles proposes giving every paragraph a stable identifier the first time a document is opened, so every later accept or reject points at a specific paragraph instead of guessing from context. The change also retires roughly eight hundred lines of hand-rolled document plumbing in favour of a maintained open-source library, and clears up a smaller bug where the preview pane didn't refresh after an edit was accepted or rejected.