A package can now be prepared in this repository before it goes public:
pkg.sh sets AUR_PUBLISH=false and steps 1-4 run as usual, so the PKGBUILD
is kept current and test-built while the publishing waits.
.tar.bz2 joins the archive types the run cleans up and gitignores; concat
carries one as a source.
Upstream moved to an "ow" electron-updater channel with a filename
suffix; latest_version checks both channels (vercmp picks the winner) and
refresh_checksums keeps the _appimage filename in sync. Also clean up
downloaded .AppImage files like the other source leftovers.