chore: lossless png compression

[ckerr]

I used this script to run lossless compression utils [zopflipng, optipng, advpng, pngcrush] dialed to maximum (e.g. advpng --shrink-insane) on all the png files in the repo.

The ugly: this is very slow, which is why I'm PR'ing the changed files instead of adding the process to a workflow.

The good: this PR reduces the total size of png files in the repo from 14,328,881 bytes to 6,536,247 bytes, a lossless savings of about 55%.

See also https://github.com/electron/website/pull/583#issuecomment-2183389109. CC @dsanders11, @BlackHole1, @erickzhao who were all active in that PR.