feat(cuts): wire PlayAlbum/PlayTrack to IQueueService.PlayRelease (§3.4 seam, P11 W1)

Header Play loads full album at index 0; row play loads at that row's index with same-track
toggle preserved; null-safe cascade fallback to direct SelectTrackStreaming when queue absent.

DeepDrftPublic.Client/Pages/CutDetail.razor

@@ -69,10 +69,8 @@ else
                     }
 
                     <div class="cut-detail-actions">
-                        @* Header Play starts the album's first track. Wired to the single-slot player
-                           today; the §3.4 queue seam means a future swap to QueueService.PlayRelease
-                           is a one-line change inside PlayAlbum, not a markup edit. Disabled until a
-                           streamable track is resolved. *@
+                        @* Header Play loads the full album into the queue at index 0 (§3.4 seam,
+                           closed P11 W1). Disabled until at least one streamable track is resolved. *@
                         <MudButton Variant="Variant.Filled"
                                    Color="Color.Secondary"
                                    StartIcon="@Icons.Material.Filled.PlayArrow"
@@ -112,15 +110,17 @@ else
             else
             {
                 <div class="cut-detail-tracklist">
-                    @foreach (var track in ViewModel.Tracks)
+                    @for (var i = 0; i < ViewModel.Tracks.Count; i++)
                     {
+                        var track = ViewModel.Tracks[i];
+                        var index = i;
                         <div class="cut-detail-track-row">
                             <span class="cut-detail-track-number">@track.TrackNumber</span>
                             <div class="cut-detail-track-play">
                                 <PlayStateIcon Track="@track"
                                                Size="Size.Medium"
                                                Color="Color.Secondary"
-                                               OnToggle="@(() => PlayTrack(track))" />
+                                               OnToggle="@(() => PlayTrack(track, index))" />
                             </div>
                             <span class="cut-detail-track-name text-truncate">@track.TrackName</span>
                         </div>
@@ -133,20 +133,23 @@ else
 
 @code {
     [CascadingParameter] public IStreamingPlayerService? PlayerService { get; set; }
+    [CascadingParameter] public IQueueService? Queue { get; set; }
 
-    // Header Play: start the album's first track. The §3.4 queue seam lives here — swapping this body
-    // to `Queue.PlayRelease(ViewModel.Tracks)` once IQueueService (track 11.F) lands is a one-line
-    // change with no other edit to this page. The queue type is not referenced here because it does
-    // not exist in this worktree.
+    // Header Play: load the full album into the queue starting at track 0.
     private Task PlayAlbum()
     {
-        var first = ViewModel.Tracks.Count > 0 ? ViewModel.Tracks[0] : null;
-        return first is null ? Task.CompletedTask : PlayTrack(first);
+        if (ViewModel.Tracks.Count == 0) return Task.CompletedTask;
+        if (Queue is not null) return Queue.PlayRelease(ViewModel.Tracks, 0);
+
+        // Queue cascade absent (prerender or non-interactive): fall back to direct single-track play.
+        return PlayerService is not null
+            ? PlayerService.SelectTrackStreaming(ViewModel.Tracks[0])
+            : Task.CompletedTask;
     }
 
-    // Row play: toggle if this track is already active, otherwise start a fresh stream. Mirrors the
-    // scaffold's own PlayTrack wiring (SessionDetail uses the same idiom for its diverged layout).
-    private async Task PlayTrack(TrackDto track)
+    // Row play: toggle if this track is already playing/paused, otherwise load the album at this
+    // row's index so playback continues to the end from the chosen track.
+    private async Task PlayTrack(TrackDto track, int index)
     {
         if (PlayerService is null) return;
 
@@ -154,9 +157,16 @@ else
         if (isThisTrack && (PlayerService.IsPlaying || PlayerService.IsPaused))
         {
             await PlayerService.TogglePlayPause();
+            return;
+        }
+
+        if (Queue is not null)
+        {
+            await Queue.PlayRelease(ViewModel.Tracks, index);
         }
         else
         {
+            // Queue cascade absent: fall back to direct single-track play.
             await PlayerService.SelectTrackStreaming(track);
         }
     }