Mechanism to stop compressiong same file multiple times

**Is your feature request related to a problem? Please describe.** Say if I have a folder of images, then I add an image to this folder and run Caesiam on the folder, it'll go ahead and re compress already compressed images. I can also compress an image multiple times with caesiam, it loses about 1% per pass. **Describe the solution you'd like** with JpegMini they stop this by inserting a tiny almost hidden metadata almost "jpegmini has been here". This stops the compression running multiple times and degrading quality of the jpeg. **Additional context** I tried searching for this but couldn't see if it already exists.