feat(slint): Linux system tray (ksni) + Wayland-safe close-to-tray

Port the Tauri tray to Slint on Linux via ksni: themed icon (auto/mono/
color), left-click window toggle, middle-click play/pause, scroll volume,
the 5-item menu, and a live tooltip reflecting the now-playing track. Tray
actions call the playback controller directly (QConnect-aware) instead of
emitting webview events. Settings reuse the shared qbz-app tray store
(per-user) wired through AppearanceState.

Window hide/show uses Slint window.hide()/show() (winit set_visible is a
no-op on Wayland) and the loop runs via run_event_loop_until_quit so a
tray-hide keeps the app alive. close-to-tray is honored on both the custom
titlebar close and the WM close (on_close_requested). minimize-to-tray is
hidden until custom window chrome exists.

cc

crates/qbz-slint/ui/app.slint

@@ -18,7 +18,7 @@ import { AppShell } from "shell/AppShell.slint";
 import { Toast } from "primitives/Toast.slint";
 
 // Re-export the state globals so the Rust layer can populate them.
-export { HomeState, HomeActions, DiscoverBrowseState, DiscoverBrowseActions, ForYouState, MixState, GenreFilterState, GenreFilterActions, AlbumState, ArtistState, NavState, ShellState, SessionState, SettingsState, AlbumActions, ArtistActions, ArtworkActions, NowPlayingState, QueueState, SearchState, SearchActions, NetworkSidebarState, NetworkSidebarActions, MusicianState, MusicianActions, LabelState, LabelActions, LocationViewState, LocationViewActions, FavoritesState, FavoritesActions, PlaylistPickerState, PlaylistPickerActions, PlaylistState, PlaylistActions, SidebarState, SidebarActions, SidebarFolderPopupState, CreatePlaylistState, CreatePlaylistActions, EditPlaylistState, EditPlaylistActions, CreateFolderState, CreateFolderActions, DragState, DragActions, PlaylistManagerState, PlaylistManagerActions, OfflineManagerState, OfflineManagerActions, LocalLibraryState, LocalLibraryActions, LibraryFoldersState, LibFolderEditState, LibraryManageActions, LibraryScanState, LibAlbumFilterState, LocalAlbumState, LocalAlbumActions, TagEditorState, TagEditorActions, FolderEditState, FolderEditActions, ToastState, TextUtil, QconnectDevState, QconnectDevice } from "state.slint";
+export { HomeState, HomeActions, DiscoverBrowseState, DiscoverBrowseActions, ForYouState, MixState, GenreFilterState, GenreFilterActions, AlbumState, ArtistState, NavState, ShellState, SessionState, SettingsState, AlbumActions, ArtistActions, ArtworkActions, NowPlayingState, QueueState, SearchState, SearchActions, NetworkSidebarState, NetworkSidebarActions, MusicianState, MusicianActions, LabelState, LabelActions, LocationViewState, LocationViewActions, FavoritesState, FavoritesActions, PlaylistPickerState, PlaylistPickerActions, PlaylistState, PlaylistActions, SidebarState, SidebarActions, SidebarFolderPopupState, CreatePlaylistState, CreatePlaylistActions, EditPlaylistState, EditPlaylistActions, CreateFolderState, CreateFolderActions, DragState, DragActions, PlaylistManagerState, PlaylistManagerActions, OfflineManagerState, OfflineManagerActions, LocalLibraryState, LocalLibraryActions, LibraryFoldersState, LibFolderEditState, LibraryManageActions, LibraryScanState, LibAlbumFilterState, LocalAlbumState, LocalAlbumActions, TagEditorState, TagEditorActions, FolderEditState, FolderEditActions, ToastState, TextUtil, QconnectDevState, QconnectDevice, AppearanceState } from "state.slint";
 
 // Which top-level screen is shown. The app starts on `splash` while it
 // restores a saved session, then resolves to `shell` or `login`.

crates/qbz-slint/ui/settings/AppearanceSettings.slint

@@ -700,12 +700,11 @@ export component AppearanceSettings inherits VerticalLayout {
     Rectangle { height: 12px; }
 
     // ===================================================================
-    // SYSTEM TRAY
+    // SYSTEM TRAY  (macOS: "MENU BAR")
     // ===================================================================
-    GroupHeader { text: @tr("SYSTEM TRAY"); }
+    GroupHeader { text: AppearanceState.is-macos ? @tr("MENU BAR") : @tr("SYSTEM TRAY"); }
 
     SettingRow {
-        unsupported: true;
         label: @tr("Enable tray icon");
         description: @tr("Show icon in system tray (requires restart)");
         QbzToggle {
@@ -716,24 +715,18 @@ export component AppearanceSettings inherits VerticalLayout {
             }
         }
     }
+    // NOTE: a separate "Minimize to tray" toggle is intentionally absent.
+    // Redirecting the window-manager minimize button to the tray requires
+    // owning that button (custom window chrome), which is not built yet, and
+    // Wayland forbids a client from intercepting the compositor's minimize.
+    // Until custom chrome lands, the option is HIDDEN (not shown disabled) and
+    // this row reads "Close to tray". When custom chrome exists, merge the two
+    // into a single "Minimize/Close to tray" control.
     SettingRow {
-        unsupported: true;
-        label: @tr("Minimize to tray");
-        description: @tr("Hide window to tray when minimizing");
-        enabled: AppearanceState.tray-enable;
-        QbzToggle {
-            checked: AppearanceState.tray-minimize-to-tray;
-            enabled: AppearanceState.tray-enable;
-            toggled(v) => {
-                AppearanceState.tray-minimize-to-tray = v;
-                AppearanceState.appearance-bool("tray-minimize-to-tray", v);
-            }
-        }
-    }
-    SettingRow {
-        unsupported: true;
         label: @tr("Close to tray");
-        description: @tr("Hide window to tray instead of quitting");
+        description: AppearanceState.is-macos
+            ? @tr("Keep playing in the menu bar instead of quitting when you close the window")
+            : @tr("Keep playing in the tray instead of quitting when you close the window");
         enabled: AppearanceState.tray-enable;
         QbzToggle {
             checked: AppearanceState.tray-close-to-tray;
@@ -744,8 +737,23 @@ export component AppearanceSettings inherits VerticalLayout {
             }
         }
     }
+    // macOS-only: switch the activation policy to .accessory while closed to
+    // the menu bar (no Dock icon). Off = Spotify-style (keep the Dock icon).
+    SettingRow {
+        visible: AppearanceState.is-macos;
+        label: @tr("Hide Dock icon when closed to menu bar");
+        description: @tr("Run as a menu-bar-only app while the window is closed. Off keeps the Dock icon (like Spotify)");
+        enabled: AppearanceState.tray-enable && AppearanceState.tray-close-to-tray;
+        QbzToggle {
+            checked: AppearanceState.tray-mac-hide-dock;
+            enabled: AppearanceState.tray-enable && AppearanceState.tray-close-to-tray;
+            toggled(v) => {
+                AppearanceState.tray-mac-hide-dock = v;
+                AppearanceState.appearance-bool("tray-mac-hide-dock", v);
+            }
+        }
+    }
     SettingRow {
-        unsupported: true;
         label: @tr("Tray icon variant");
         description: @tr("Pick a mono glyph to match your panel (Plasma, GNOME's permanently dark top bar) or the full colour vinyl logo");
         QbzSelect {

crates/qbz-slint/ui/state.slint

@@ -1432,9 +1432,15 @@ export global AppearanceState {
     in-out property <bool> show-purchases: false;
 
     // --- SYSTEM TRAY -------------------------------------------------------
+    // `is-macos` is set once from Rust (cfg!(target_os = "macos")) so the tray
+    // section can swap the header to "Menu Bar" and show macOS-only controls.
+    in-out property <bool> is-macos: false;
     in-out property <bool> tray-enable: true;
     in-out property <bool> tray-minimize-to-tray: false;
     in-out property <bool> tray-close-to-tray: false;
+    // macOS-only: hide the Dock icon when closed to the menu bar (.accessory
+    // activation policy). Off = Spotify-style (keep the Dock icon).
+    in-out property <bool> tray-mac-hide-dock: false;
     in-out property <[string]> tray-icon-themes: ["Auto", "Mono light", "Mono dark", "Color"];
     in-out property <int> tray-icon-theme-index: 0;