vt: pad double-width code points with a zero-white-space

vt: pad double-width code points with a zero-white-space

In the Unicode screen buffer, we follow double-width code points with a
space to maintain proper column alignment. This, however, creates
semantic problems when e.g. using cut and paste or selection.

Let's use a better code point for the column padding's purpose i.e. a
zero-white-space rather than a full space.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Link: https://lore.kernel.org/r/20250410011839.64418-12-nico@fluxnic.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>