Linux-Port: GNOME-Popup + Tray, Terminal-Schriftgröße global

- Popup als rahmenloses Fenster mit D-Bus-Relay (popup.html/ts, Popup.vue);
  GNOME-Extension schiebt es unter den Panel-Button
- Terminal: globale Schriftgröße via settings.json (terminalFontSize),
  Zoom mit Ctrl/Cmd +/-/0 im Terminal
- trayLinux-Icon, Capabilities, App.vue/terminal.html angepasst

src-tauri/Cargo.toml

@@ -31,6 +31,10 @@ portable-pty = "0.9"
 uuid = { version = "1", features = ["v4"] }
 keyring = { version = "3", features = ["apple-native", "sync-secret-service", "windows-native"] }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+zbus = "5"
+glib = "0.18"
+
 [target.'cfg(target_os = "macos")'.dependencies]
 objc2 = "0.6"
 objc2-app-kit = { version = "0.3", features = ["NSApplication", "NSImage", "NSResponder", "NSRunningApplication"] }