Linux and macOS support #74

Idea

Bring Console Mode to Linux (desktop and handheld distros like SteamOS/Bazzite) and macOS: one click to focus the TV, turn off the other screens, switch audio, launch the game UI, and restore everything afterwards.

Why it's a big one

Today the app is Windows-only by design, not just by packaging:

• UI: WinUI 3 / Windows App SDK, which only runs on Windows.
• Displays: Windows CCD APIs (SetDisplayConfig), MultiMonitorTool, HDR/VRR toggles.
• Audio: Windows audio endpoints (SoundVolumeView).
• Controllers: XInput, Windows.Gaming.Input, and the Sony HID reader (hid.dll / SetupAPI).
• Session: Steam Big Picture / Xbox app / Playnite detection, RTSS for the FPS limit, tray, named-pipe control API, Inno Setup installer and updater.

Possible path

1. Split a platform-neutral core (config, session flow, rules like UiModeResolver and ControllerMapping) from the Windows services behind interfaces.
2. Pick a cross-platform UI: Avalonia or Uno Platform (both C#, closest to the current XAML), or keep WinUI on Windows and add a thin UI per OS.
3. Per-OS backends:
   • Linux: displays via xrandr (X11) or wlr-randr / KDE kscreen-doctor / GNOME Mutter D-Bus (Wayland); audio via PipeWire/PulseAudio (pactl/wpctl); controllers via SDL2 or evdev; launch steam -gamepadui or Gamescope.
   • macOS: displays via CoreGraphics (CGDisplay*, mirroring/disable where allowed); audio via CoreAudio; controllers via GameController.framework; launch Steam Big Picture.
4. Packaging: AppImage/Flatpak on Linux, a signed .app / DMG on macOS; the updater per platform.

Open questions

• Which platform first? Linux handhelds and HTPCs look like the closest fit.
• Wayland makes turning outputs off compositor-specific; how many compositors to support at first?
• Is there interest? 👍 this issue if you'd use it, and say which distro/desktop or Mac you have.

Not planned for a specific version yet.