Saves an image to the gallery and additionally exports a copy to the
filesystem with a custom filename using prefix and suffix around the
gallery UUID.
- Filename pattern: {prefix}{uuid}{suffix}.{png|jpg|webp}
- UUID matches the gallery entry so exported files can be matched back
- Quality input (1-100) for JPG/WEBP, ignored for PNG
- Board and Metadata inputs behave like the standard Save Image node
- Output directory restricted to subfolders of the InvokeAI outputs
folder; absolute paths and path traversal are rejected
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