feat(slint): clickable artist name on AlbumCard -> artist page

Ports Tauri's behavior where clicking an album card's artist name
navigates to that artist (the card body still opens the album).

  - AlbumCardItem gains artist-id; populated in every album-card
    constructor (home/search/label/foryou/favorites). Artist-page
    release cards leave it empty (their subtitle slot shows the year,
    not the artist, so it stays non-clickable).
  - AlbumCard wraps the artist name in a TouchArea that emits
    media-action("artist", artist-id, "open") and brightens on hover
    only when an id is known.
  - main.rs handles ("artist","open") -> open the artist page;
    FavoritesView (which only forwarded clicked) now forwards the
    artist action.

cc

crates/qbz-slint/ui/discover/AlbumCard.slint

@@ -286,13 +286,26 @@ export component AlbumCard inherits Rectangle {
                     vertical-alignment: center;
                     overflow: elide;
                 }
-                Text {
-                    text: root.album.artist;
+                // Artist name — clickable when an artist id is known,
+                // navigating to the artist page (1:1 with Tauri).
+                artist-area := TouchArea {
                     height: 18px;
-                    color: Theme.text-muted;
-                    font-size: Typography.link;
-                    vertical-alignment: center;
-                    overflow: elide;
+                    width: artist-text.preferred-width;
+                    mouse-cursor: root.album.artist-id != "" ? pointer : default;
+                    clicked => {
+                        if (root.album.artist-id != "") {
+                            root.media-action("artist", root.album.artist-id, "open");
+                        }
+                    }
+                    artist-text := Text {
+                        text: root.album.artist;
+                        color: root.album.artist-id != "" && artist-area.has-hover
+                            ? Theme.text-primary
+                            : Theme.text-muted;
+                        font-size: Typography.link;
+                        vertical-alignment: center;
+                        overflow: elide;
+                    }
                 }
             }