[feature] live-edit of change detection text to test text filters etc

Small idea, at /diff, if we could edit the text inline then it might be handy for working out if the filters matched or not

maybe also for /edit

Start at the /diff view and inspect how the displayed change-detection text and filters are presented; also check the /edit view mentioned in the issue. Done means text can be edited inline in the relevant view and the filters can be tested against the edited content.

Written by the indexing model from the issue text.