3484

Compile the images into the executable

The PNG and SVG files in TS/images are turned into a generated header
at build time (cmake/EmbedImages.cmake) and loaded from memory, so they
no longer have to be installed next to the executable. Only the
licenses of the icon sets are installed, into the documentation
directory. The image dropdown lists the built-in images in name order.
The unused line_ne/line_se images are removed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>