Add --install-desktop to install a desktop entry

Detects an installed terminal emulator (kitty, alacritty, wezterm, foot,
ghostty, gnome-terminal, konsole, xfce4-terminal, tilix,
x-terminal-emulator, xterm) and bakes an explicit launch command into
the entry, since Terminal=true is unreliable on modern desktops.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

src/config.rs

@@ -21,6 +21,10 @@ pub struct CliArgs {
     /// Path to config file. Defaults: ./config.toml then $XDG_CONFIG_HOME/emby-client/config.toml
     #[arg(short, long)]
     pub config: Option<PathBuf>,
+
+    /// Install a desktop entry for the current executable and exit
+    #[arg(long)]
+    pub install_desktop: bool,
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]