feat(albumcard): add show-favorite flag to hide the heart in non-favoritable contexts

The shared AlbumCard always rendered the favorite heart (overlay button +
"Add to favorites" menu item). Local Library albums are not Qobuz-favoritable
(Tauri's AlbumCardLibraryLite hides favorite/genre), so the upcoming local
grid needs to suppress it.

Add an additive `show-favorite: bool` (default true) on AlbumCard, threaded
through AlbumCollectionView -> AlbumGrid. The fav overlay button uses
`visible:` (not an `if`) so it stays referenceable by `overlay-on` (keeping
the Qobuz hover-no-flicker behavior intact); the menu item is gated with an
`if`. All existing callers (Discover / Favorites / Label) default to true,
so behavior is unchanged.

cc

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

@@ -61,6 +61,9 @@ component OverlayButton inherits Rectangle {
 
 export component AlbumCard inherits Rectangle {
     in property <AlbumCardItem> album;
+    // Hide the favorite heart + its menu item in non-favoritable contexts
+    // (e.g. Local Library albums). Mirrors Tauri's AlbumCardLibraryLite.
+    in property <bool> show-favorite: true;
     // Fade out when the card is being removed (favorites un-favorite).
     opacity: root.album.removing ? 0.0 : 1.0;
     animate opacity { duration: 250ms; }
@@ -159,6 +162,7 @@ export component AlbumCard inherits Rectangle {
                 VerticalLayout {
                     alignment: center;
                     fav-btn := OverlayButton {
+                        visible: root.show-favorite;
                         icon: root.album.is-favorite
                             ? @image-url("../assets/icons/heart-filled.svg")
                             : @image-url("../assets/icons/heart.svg");
@@ -263,7 +267,7 @@ export component AlbumCard inherits Rectangle {
                             root.media-action("album", root.album.id, "queue");
                         }
                     }
-                    ContextMenuItem {
+                    if root.show-favorite: ContextMenuItem {
                         icon: @image-url("../assets/icons/heart.svg");
                         label: @tr("Add to favorites");
                         clicked => {

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

@@ -18,6 +18,7 @@ component AlbumGrid inherits Rectangle {
     in property <length> card-width: 220px;
     in property <length> card-height: 266px;
     in property <length> card-gap: 24px;
+    in property <bool> show-favorite: true;
     callback open-album(string);
     callback open-artist(string);
     callback media-action(string, string, string);
@@ -36,6 +37,7 @@ component AlbumGrid inherits Rectangle {
         width: root.card-width;
         height: root.card-height;
         album: album;
+        show-favorite: root.show-favorite;
         clicked(id) => {
             root.open-album(id);
         }
@@ -55,6 +57,9 @@ export component AlbumCollectionView inherits VerticalLayout {
     in property <bool> is-grouped: false;
     in property <string> view-mode: "grid";       // "grid" | "list"
     in property <bool> show-source: false;
+    // Forwarded to AlbumCard — hide the favorite heart in non-favoritable
+    // contexts (Local Library albums).
+    in property <bool> show-favorite: true;
     in property <length> card-width: 220px;
     in property <length> card-height: 266px;
     in property <length> card-gap: 24px;
@@ -103,6 +108,7 @@ export component AlbumCollectionView inherits VerticalLayout {
             // Grid view: a card grid for this section.
             if root.view-mode != "list": AlbumGrid {
                 albums: section.albums;
+                show-favorite: root.show-favorite;
                 card-width: root.card-width;
                 card-height: root.card-height;
                 card-gap: root.card-gap;
@@ -122,6 +128,7 @@ export component AlbumCollectionView inherits VerticalLayout {
     // --- Flat grid -----------------------------------------------------
     if !root.is-grouped && root.view-mode == "grid" && root.albums.length > 0: AlbumGrid {
         albums: root.albums;
+        show-favorite: root.show-favorite;
         card-width: root.card-width;
         card-height: root.card-height;
         card-gap: root.card-gap;