ImageMagick 6 convert cannot run `identify` as a subcommand; use Pillow
mode so Gitea runners without magick pass the composite color check.
Co-authored-by: Cursor <cursoragent@cursor.com>
Add darktable style probe and pytest integration/slow markers so CI and
machines without a working darktable-cli setup skip the full workflow test.
Co-authored-by: Cursor <cursoragent@cursor.com>