feat(slint): Label landing page + All Releases sub-view

Port the Tauri LabelView module to native Slint, reusing existing
components and extending where needed (no duplication).

Landing (new LabelPageView): circular header + description read-more +
Follow toggle, sticky JUMP TO bar, Popular Tracks (multi-select, 5->20->50
reveal, Play all), and Releases (+ See all) / Critics' Picks / Playlists /
Artists / More Labels carousels.

All Releases sub-view (LabelReleasesView): circular header + album count,
toolbar (local search, group-by-artist, Hi-Res filter, sort) + grid/list
toggle, load-more, states. TYPE column now populated.

Split the label route: ContentView::label -> LabelPageView (landing),
ContentView::label-releases -> LabelReleasesView; add NavEntry::LabelReleases.
label.rs load_label_page parses /label/page + getAlbums + explore + the
favorite-labels set; derive_releases re-derives the sub-view list.
Reuse Carousel/PlaylistCarousel/ArtistCarousel/TrackRow/AlbumCard/
AlbumListRow/JumpNavBar/QbzSelect/ExpandableSearch; extend ArtistCard/
ArtistCarousel (follow-mode/follow-kind); promote CircleAction to a shared
primitive; JumpNavBar gains show-search. Wire label media-actions:
follow, play-top, open (more-labels), see-all.

cc

crates/qbz-slint/ui/shell/AppShell.slint

@@ -25,6 +25,7 @@ import { AlbumPageView } from "../album/AlbumPageView.slint";
 import { ArtistPageView } from "../artist/ArtistPageView.slint";
 import { MusicianPageView } from "../musician/MusicianPageView.slint";
 import { LabelReleasesView } from "../label/LabelReleasesView.slint";
+import { LabelPageView } from "../label/LabelPageView.slint";
 import { ArtistsByLocationView } from "../location/ArtistsByLocationView.slint";
 import { FavoritesView } from "../favorites/FavoritesView.slint";
 import { MixView } from "../mix/MixView.slint";
@@ -132,7 +133,18 @@ export component AppShell inherits Rectangle {
                         root.open-album(id);
                     }
                 }
-                if NavState.view == ContentView.label: LabelReleasesView {
+                if NavState.view == ContentView.label: LabelPageView {
+                    open-album(id) => {
+                        root.open-album(id);
+                    }
+                    open-artist(id) => {
+                        root.open-artist(id);
+                    }
+                    media-action(kind, id, action) => {
+                        root.media-action(kind, id, action);
+                    }
+                }
+                if NavState.view == ContentView.label-releases: LabelReleasesView {
                     open-album(id) => {
                         root.open-album(id);
                     }