tauri-app: tray settings menu item

Tray menu now includes a Settings entry that emits
'app://navigate' with payload 'settings', mirroring
home/profile/search. client.ts listenTrayEvents type
extended to include 'settings'.

crates/tauri-app/src-tauri/src/lib.rs

@@ -606,6 +606,14 @@ pub fn run() {
                 None::<&str>,
             )
             .map_err(|e| format!("failed to build search menu item: {e}"))?;
+            let settings_item = tauri::menu::MenuItem::with_id(
+                app,
+                "tray_settings",
+                "Settings",
+                true,
+                None::<&str>,
+            )
+            .map_err(|e| format!("failed to build settings menu item: {e}"))?;
             let quit_item = tauri::menu::MenuItem::with_id(
                 app,
                 "tray_quit",
@@ -625,6 +633,7 @@ pub fn run() {
                     &compose_item,
                     &profile_item,
                     &search_item,
+                    &settings_item,
                     &separator,
                     &quit_item,
                 ],
@@ -653,6 +662,9 @@ pub fn run() {
                     "tray_search" => {
                         let _ = tauri::Emitter::emit(app, "app://navigate", "search");
                     }
+                    "tray_settings" => {
+                        let _ = tauri::Emitter::emit(app, "app://navigate", "settings");
+                    }
                     "tray_quit" => {
                         app.exit(0);
                     }