Modul-Split: Fachlogik nach domain/, OS-Code nach platform/, Tauri-Verdrahtung in app.rs/commands.rs

- lib.rs nur noch Prozessrollen-Dispatch + Panic-Tracer
- KWin-Script als KDE-Pendant zur GNOME-Extension (Popup ans Zeiger-
  Rechteck), wird von deb/rpm mit ausgeliefert
- SNI-Tray auf ksni (pure Rust), appindicator-Depends entfallen

src-tauri/Cargo.toml

@@ -39,6 +39,7 @@ keyring = { version = "3", features = ["apple-native", "sync-secret-service", "w
 zbus = "5"
 glib = "0.18"
 rfd = { version = "0.15", default-features = false, features = ["gtk3"] }
+ksni = "0.1"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 objc2 = "0.6"