fcd36f34d1
On a headless GNOME host the xdg-desktop-portal RemoteDesktop Start() blocks on an
interactive "Allow remote control?" approval nobody can click, so libei input timed out
("EIS setup timed out") and neither mouse nor keyboard worked — even though video worked
(it uses Mutter's direct RemoteDesktop API).
Add EiSource::MutterEis: obtain the EIS fd from
org.gnome.Mutter.RemoteDesktop.Session.ConnectToEIS (CreateSession → Start → ConnectToEIS),
no portal and no approval. Selected for GNOME/Mutter; KWin keeps the RemoteDesktop portal,
gamescope keeps its own EIS socket.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>