bug#81583: 32.0.50; Optional preview of the replacement text while typing it

I'm opening this as a bug, as suggested by Juri Linkov.

This proposes an optional live preview of the replacement while
typing in 'query-replace' and 'query-replace-regexp': as the
replacement string is entered, visible matches in the buffer are
updated to show what the replacement will look like.

The discussion (with screenshots) on 'emacs-devel' is here:

https://lists.gnu.org/archive/html/emacs-devel/2026-08/msg00195.html

The proposed implementation adds a 'query-replace-show-preview' option,
which defaults to 'nil'.  When enabled, matches visible in the selected
window are displayed as they would look after the replacement, using a
new 'query-replace-preview' face.

The preview is limited to matches visible in the selected window, and
replacement length changes are reflected while typing.

I'll post the patch in a follow-up message once this report has been
assigned a bug number.

-- 
Rahul Martim Juliato