Fix Steam login flicker with 2GB shm and stable launch scripts.

Use tini-backed entrypoint, two-phase Steam startup, and a window keeper so CEF UI and the fluxbox toolbar stay visible in Moonlight.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/entrypoint.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+set -e
+
+rm -f /tmp/.X99-lock /tmp/.X11-unix/X99
+
+id steam >/dev/null 2>&1 || useradd -m -s /bin/bash steam
+mkdir -p /home/steam/.local/share/Steam /tmp/xdg-steam /home/steam/tmp
+ln -sfn /home/steam/.local/share/Steam /home/steam/.steam
+chown -R steam:steam /home/steam /tmp/xdg-steam
+
+mkdir -p /run/dbus
+rm -f /run/dbus/pid
+dbus-daemon --system --fork || true
+
+Xorg :99 -config /etc/X11/xorg-dummy.conf -nolisten tcp -noreset \
+  +extension GLX +extension RANDR +extension RENDER &
+
+export DISPLAY=:99
+export HOME=/root
+export LANG=en_US.UTF-8
+export LC_ALL=en_US.UTF-8
+
+mkdir -p /root/.fluxbox
+cp -f /etc/game-server/fluxbox/init /root/.fluxbox/init
+
+sleep 3
+fluxbox &
+sleep 2
+xsetroot -solid "#3c3c3c" 2>/dev/null || true
+
+exec /usr/bin/sunshine