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/usr/bin/bc250-steam-bpm-autostart

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+# Autostart Steam Big Picture Mode for the kid's account only.
+# Other accounts (parent, RDP admin sessions) get a normal desktop.
+[ "$(id -un)" = "kid" ] || exit 0
+exec /usr/bin/bazzite-steam-bpm