Console plug-and-play layer: always-on, BPM autostart, game launchers

- Mask all suspend paths + dconf no-sleep/no-lock defaults (local + GDM):
  the console must stay reachable over SSH/RDP at all times
- Autostart Steam Big Picture Mode for the kid account only
- Enable tailscaled (idle until 'tailscale up')
- First-boot flatpaks: ProtonUp-Qt, Heroic, RetroDECK

Already in the bazzite base, so not added: Steam, Tailscale, automatic
updates (uupd.timer), Firefox via first-boot flatpak manager.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

files/console/etc/xdg/autostart/bc250-steam-bpm.desktop

@@ -0,0 +1,7 @@
+[Desktop Entry]
+Type=Application
+Name=Steam Big Picture (console autostart)
+Comment=Launches Steam in Big Picture Mode when the kid logs in
+Exec=/usr/bin/bc250-steam-bpm-autostart
+X-GNOME-Autostart-enabled=true
+NoDisplay=true