[Feature Request] Save workflow alongside image

Would it be possible to save the workflow that generated an image alongside the image in the output directory? Essentially the same name as the image, but with a `.json` extension. This could be a simple boolean input in the save image node to trigger the saving of the workflow.

This would be for single and batched images, where batched images save the specific workflow used for them (including seeds - same with single images). This would allow you to go back and review the workflow used on any given image at any time in the future.

No file or test is named. Start by locating the save image node and the output path handling, then trace how single and batched images retain their workflow and seeds. Done means an optional setting writes a same-basename .json workflow beside each image, including the workflow specific to each batch item.

Written by the indexing model from the issue text.