feat(slint): favorites Artists header Shuffle (random artist)

Add a Shuffle CircleAction to the Artists row-2 action cluster that opens a
random artist from the visible set (random ARTIST, not a random album —
matches Tauri). Adds favorites::random_visible_artist + the artists-shuffle
handler routing through invoke_open_artist.

cc

crates/qbz-slint/src/favorites.rs

@@ -809,6 +809,22 @@ pub fn random_visible_album(window: &AppWindow) -> Option<String> {
     model.row_data(idx).map(|a| a.id.to_string())
 }
 
+/// A random artist id from the currently-visible favorites set. Tauri's
+/// Artists header Shuffle opens a random ARTIST (not a random album).
+pub fn random_visible_artist(window: &AppWindow) -> Option<String> {
+    let model = window.global::<FavoritesState>().get_artists_visible();
+    let n = model.row_count();
+    if n == 0 {
+        return None;
+    }
+    let seed = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .map(|d| d.as_nanos() as u64)
+        .unwrap_or(1);
+    let idx = (seed % n as u64) as usize;
+    model.row_data(idx).map(|a| a.id.to_string())
+}
+
 // ---- Un-favorite in place: fade (set `removing`) then remove -----------
 
 /// Flag the matching track row(s) as removing so they fade out.

crates/qbz-slint/src/main.rs

@@ -4362,6 +4362,20 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
                 }
             });
     }
+    {
+        // Artists header Shuffle = open a random visible artist (random
+        // ARTIST, not a random album — matches Tauri).
+        let weak = window.as_weak();
+        window
+            .global::<FavoritesActions>()
+            .on_artists_shuffle(move || {
+                if let Some(w) = weak.upgrade() {
+                    if let Some(id) = favorites::random_visible_artist(&w) {
+                        w.invoke_open_artist(id.into());
+                    }
+                }
+            });
+    }
     {
         // Playlist card actions: play / play-next / queue / share / favorite.
         let runtime = app_runtime.clone();

crates/qbz-slint/ui/favorites/FavoritesView.slint

@@ -635,6 +635,19 @@ export component FavoritesView inherits Rectangle {
                     }
                 }
             }
+            if FavoritesState.active-tab == "artists"
+                && FavoritesState.artists-visible.length > 0: HorizontalLayout {
+                spacing: 8px;
+                VerticalLayout {
+                    alignment: center;
+                    CircleAction {
+                        icon: @image-url("../assets/icons/shuffle.svg");
+                        clicked => {
+                            FavoritesActions.artists-shuffle();
+                        }
+                    }
+                }
+            }
 
             Rectangle { horizontal-stretch: 1; }