I made artifacts/image.png: a 512 × 512 PNG (8-bit RGB) of a flat purple square centered on a near-black background. All the visual requirements are met.

• Colors: I counted every pixel and the file contains exactly two colors: purple #8c52d6 and background #0e0e12. That rules out any gradient, texture, shadow, border or text.
• Square: 396 × 396 px, with a 58 px margin on every side, so it's exactly centered.
• Coverage: 59.8% of the canvas area.
• Visual check: I opened the image and it looks as described.

Decision for you: I read "about 60% of the canvas" as 60% of the area. If you meant the square's side should be 60% of the canvas width, it would be about 307 px instead. That's a one-line change if you want it.

I also wrote a short artifacts/README.md that records the dimensions, format, how the image was made and this interpretation. Both files are untracked, as instructed.