If your talking about a source distribution archive, generally it is the project in the ‘distclean’ state. This is decribed in GNU documentation. I think for GNU Make. Not sure if the git specific files should technically be included but maybe these days they should. The ‘distclean’ state is generally the same code as from the VCS tree but with hard to build files pre-built but probably not platform specific files. The ‘maintainerclean’ state is basically the clean VCS snapshot nothing pre-built.
Edit: The reason to prebuild some not platform specific files is to minimize the tools needed for installing from source.
By the way. The only files you mentioned I am less sure about are configs. Specifically if these configs are system specific, probaby only examples or templates should be included but the configs should be built by the build process on the target system.
Edit: It should contain tests. Running some equivalent to ‘make check’ on the target system is pretty standard.
Edit: Not sure what .github folder tree file contains so cannot say.