Add a top-level publish config in electron-builder.json5 pointing to
GitHub Releases. This embeds the update information URL in the AppImage
header, enabling tools like AppImageUpdate, AppImageLauncher, and
AppManager to perform delta updates instead of full re-downloads.
Also update the Linux build workflow to upload the generated .zsync file
alongside the .AppImage artifact.
Fixes#219
Change compression from "maximum" to "normal" for electron-builder.
The "maximum" compression setting causes gzip/xz compression in the
squashfs filesystem, which has extremely poor random access performance
(~35 MB/s). This results in 50+ second boot times on Linux AppImage
releases due to FUSE overhead during Electron's many small file reads
at startup.
With "normal" compression, the AppImage uses faster decompression
algorithms, dramatically improving startup time while only marginally
increasing package size.
Refs: electron-userland/electron-builder#6317
Refs: electron-userland/electron-builder#7483
Trevin Chow