feat(qbz-qt): phase 13 — correct card families in Library + Discover tabs

Library audit: the phase-7 conversion never actually mounted the shared
AlbumCard — ALL kinds used the invented feed card. Now per-kind 1:1:
LibTrackCard (discover/TrackCard replica with wired next/later/queue
enqueue), shared AlbumCard for albums, LibArtistCard (ArtistGridCard
circle), LibPlaylistCard (collage, follow-aware), LibLabelCard
(gradient + contain-fit logo), list rows rewritten to the real
FavoritesView inline row, Tracks tab on a TrackRow replica. Discover:
Editor's Picks and For You tabs rendered from the same discover-index
fetch, prefs-ordered per DiscoverPrefsStore (incl. mostStreamed#album
variant, Qobuz Mixes gradient tiles, Pinned in the user's own position);
Recommendations tab gated on the user's pref with an explicit engine
placeholder. No refetch on tab switches.

km

crates/qbz-qt/qml/Main.qml

@@ -40,6 +40,7 @@ ApplicationWindow {
     Component.onCompleted: QbzBridge.boot()
 
 
+
     Loader {
         id: screenLoader
         anchors.fill: parent