feat(qbz-qt): phase 4 — live playback, queue, and transport via QbzCore

Album-card click plays the album: get_album -> QueueTrack vec ->
set_queue -> play_track_resolved (tier walk stays in the core). 1 Hz
poll publishes position/meta/quality into the NowPlaying model; end-of-
track edge auto-advances with meta refresh (traced live: 24-bit/48kHz
CMAF stream, position advancing, track 2/3 transitions). Transport
invokables rewired to real core calls; queue panel shows NOW PLAYING +
numbered UP NEXT from get_queue_state. Public QbzCore API proved
sufficient — protected audio/player crates untouched. Named gaps:
no mute API, no playback event stream, auto-advance/prefetch semantics
remain frontend glue (~150 lines every UI must port).

km

crates/qbz-qt/src/bridge.rs

@@ -178,6 +178,11 @@ pub mod qbz_bridge {
         /// index + rails and republish `homeSectionsJson`.
         #[qinvokable]
         fn reload_home(self: Pin<&mut QbzBridge>);
+
+        /// Album-card click on Home: resolve the album's tracks, enqueue,
+        /// and play through the core's resolved path.
+        #[qinvokable]
+        fn play_album(self: Pin<&mut QbzBridge>, album_id: QString);
     }
 
     impl cxx_qt::Threading for QbzBridge {}
@@ -340,38 +345,42 @@ impl qbz_bridge::QbzBridge {
     }
 
     pub fn toggle_play(self: Pin<&mut Self>) {
-        crate::now_playing::toggle_play();
+        crate::transport_toggle_play();
     }
 
     pub fn next(self: Pin<&mut Self>) {
-        crate::now_playing::next();
+        crate::transport_next();
     }
 
     pub fn previous(self: Pin<&mut Self>) {
-        crate::now_playing::previous();
+        crate::transport_previous();
     }
 
     pub fn seek(self: Pin<&mut Self>, frac: f32) {
-        crate::now_playing::seek(frac);
+        crate::transport_seek(frac);
     }
 
     pub fn set_volume(self: Pin<&mut Self>, volume: f32) {
-        crate::now_playing::set_volume(volume);
+        crate::transport_set_volume(volume);
     }
 
     pub fn toggle_mute(self: Pin<&mut Self>) {
-        crate::now_playing::toggle_mute();
+        crate::transport_toggle_mute();
     }
 
     pub fn toggle_shuffle(self: Pin<&mut Self>) {
-        crate::now_playing::toggle_shuffle();
+        crate::transport_toggle_shuffle();
     }
 
     pub fn cycle_repeat(self: Pin<&mut Self>) {
-        crate::now_playing::cycle_repeat();
+        crate::transport_cycle_repeat();
     }
 
     pub fn reload_home(self: Pin<&mut Self>) {
         crate::reload_home();
     }
+
+    pub fn play_album(self: Pin<&mut Self>, album_id: QString) {
+        crate::play_album(album_id.to_string());
+    }
 }