feat(slint): full track context menu (13 items, ported from Tauri)

New shared TrackContextMenu primitive with every option the Tauri
TrackMenu shows (flat — no submenus): Play now / Play next / Add to
queue / Create radio / Add to library / Add to mixtape / Add to
playlist / Share Qobuz link / Share Song.link / Make available offline
/ Go to album / Go to artist / Track info. Items already wired in the
MVP (play / play-next / queue / favorite) fire as before; the rest emit
their media-action and stay no-op until the backend lands. Used by
SearchTrackRow, AlbumPageView TrackRow, and ArtistPageView TrackRow.

cc

crates/qbz-slint/ui/artist/ArtistPageView.slint

@@ -13,6 +13,7 @@ import { QbzIcon } from "../primitives/QbzIcon.slint";
 import { ContextMenu } from "../primitives/ContextMenu.slint";
 import { ContextMenuItem } from "../primitives/ContextMenuItem.slint";
 import { TrackPlayCell } from "../primitives/TrackPlayCell.slint";
+import { TrackContextMenu } from "../primitives/TrackContextMenu.slint";
 import { Carousel } from "../discover/Carousel.slint";
 import { NavButtons } from "../shell/NavButtons.slint";
 
@@ -147,40 +148,12 @@ component TrackRow inherits Rectangle {
         }
     }
 
-    track-menu := PopupWindow {
-        x: parent.width - 208px;
+    track-menu := TrackContextMenu {
+        x: parent.width - self.width - 12px;
         y: 44px;
-        width: 196px;
-        height: 109px;
-        ContextMenu {
-            ContextMenuItem {
-                icon: @image-url("../assets/icons/play.svg");
-                label: @tr("Play");
-                clicked => {
-                    root.media-action("track", root.track.id, "play");
-                }
-            }
-            ContextMenuItem {
-                icon: @image-url("../assets/icons/list-plus.svg");
-                label: @tr("Play next");
-                clicked => {
-                    root.media-action("track", root.track.id, "play-next");
-                }
-            }
-            ContextMenuItem {
-                icon: @image-url("../assets/icons/list-end.svg");
-                label: @tr("Add to queue");
-                clicked => {
-                    root.media-action("track", root.track.id, "queue");
-                }
-            }
-            ContextMenuItem {
-                icon: @image-url("../assets/icons/heart.svg");
-                label: @tr("Add to favorites");
-                clicked => {
-                    root.media-action("track", root.track.id, "favorite");
-                }
-            }
+        track-id: root.track.id;
+        media-action(k, i, a) => {
+            root.media-action(k, i, a);
         }
     }
 }