slide-maker through 5.8.0 Path Traversal via generate_images_openai.py

slide-maker through 5.8.0 contains a path traversal vulnerability in generate_images_openai.py that allows attackers to write image files outside the output directory via manifest-supplied filenames. Attackers can influence deck source material so the image prompt manifest contains ../ or symlinked filenames, creating directories and overwriting existing files at arbitrary paths.