feat(power): logout via loginctl, not Niri-locked

Default `loginctl terminate-session $XDG_SESSION_ID`; `logout_command`
TOML override for other compositors.

README.md

@@ -15,6 +15,13 @@ A fullscreen overlay triggered by keybind with 5 actions:
 - DE/EN localization
 - Configurable wallpaper (TOML)
 
+## Requirements
+
+- A Wayland compositor with `wlr-layer-shell` (Moonarch targets **Niri**)
+- A systemd-logind session for the default logout (`loginctl terminate-session`); other setups can override via `logout_command`
+- Runtime: `gtk4`, `gtk4-layer-shell`
+- Build: `cargo`, `git`
+
 ## Installation
 
 ```bash
@@ -47,6 +54,10 @@ Config file: `~/.config/moonset/moonset.toml` or `/etc/moonset/moonset.toml`
 ```toml
 # Path to background image (optional)
 background_path = "/usr/share/moonarch/wallpaper.jpg"
+
+# Logout command override (optional)
+# Default: loginctl terminate-session $XDG_SESSION_ID
+logout_command = "niri msg action quit"
 ```
 
 Wallpaper fallback: config → `/usr/share/moonarch/wallpaper.jpg` → bundled package wallpaper
@@ -67,3 +78,7 @@ cargo build --release
 - **moongreet** — greetd greeter for Wayland
 - **moonlock** — Wayland lockscreen
 - **moonset** — Session power menu
+
+## License
+
+MIT