v4.0.4

Eagle for Linux v4.0.4

A follow-up to v4.0.3 fixing one thing: "start hidden" was being ignored on
rpm, Arch and Nix installs.

Launch at login now honours "start hidden" everywhere
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When enabling autostart, Eagle prefers copying the installed eagle.desktop
over writing a fresh entry, and that copy was verbatim. The installed file
launches Eagle normally, so the "start hidden" preference was silently
dropped on every rpm, Arch and Nix install - autostart worked, but the window
always appeared. Flatpak and AppImage were unaffected.

The Exec line is now rewritten while copying, inserting --hidden ahead of any
desktop field codes, so "Exec=eagle %u" becomes "Exec=eagle --hidden %u".

If you already had launch-at-login enabled, toggle it off and on once to
regenerate the entry.

Everything from v4.0.3 is included: imported and renamed items no longer
collapse to "_", the Flatpak launches, and autostart works under Flatpak and
AppImage. Existing items already named "_" will not repair themselves and
need re-importing.

Fedora users need RPM Fusion for ffmpeg with proprietary codecs.