message: Changelog.md: Cleanup.
diff: - [Linux] Changes the .desktop file name and icon file name to conform to the flatpak recommendations.
  - [Linux] Provide an AppStream XML file.
  - [Linux] Drop KDE/KWin dependency on the binary by implementing enabling blur-behind background manually.
  -- [Linux] Adds support for blur-behind window on GNOME shell (Please read https://github.com/aunetx/blur-my-shell/issues/300 for further details if in trouble).
  +- [Linux] Adds support for blur-behind window on GNOME shell.
  - Changes behavior of PTY (and shell process) creation until only when a PTY is required by the terminal emulator during instanciation, possibly avoiding problems with xdotool running too early.
  - Internal: Y-axis inverted to match GUI coordinate systems where (0, 0) is top left rather than bottom left.
  