I want the filenames of my photos (and videos) to contain the creation timestamp.

YYYY-MM-dd_HH.mm.ss.jpg  # e.g. 1234-12-12_12.34.56.jpg

It uses the EXIF OrigDateTime tag of .jpg files. If there is no EXIF tag it will use the filename to extract datetime information. .mp4 files also get their filename parsed.

To publish a release ready to run as a self contained executable just

cd ImageRenamer.Wpf
dotnet publish -c Release

Then copy the entire resulting publish folder somewhere and create a shortcut to the desktop or not. "Self-contained" and "singlefile" are slightly missleading. All the other stuff in the publish folder are required to run. (Not the .pdb files if you don't want to debug.)