Reflect real playback state on gallery cards and toggle pause/resume

Add IsPaused/OnPause to TrackCard, make TracksGallery controlled, and
drive the active track from PlayerService.CurrentTrack as the single
source of truth.

DeepDrftShared.Client/Components/TracksGallery.razor.cs

@@ -6,18 +6,20 @@ namespace DeepDrftShared.Client.Components;
 public partial class TracksGallery : ComponentBase
 {
     [Parameter] public IEnumerable<TrackDto> Tracks { get; set; } = [];
-    [Parameter] public TrackDto? SelectedTrack { get; set; }
-    [Parameter] public EventCallback<TrackDto?> SelectedTrackChanged { get; set; }
 
-    private async Task HandlePlayClick(TrackDto track)
-    {
-        if (SelectedTrack == track) return;
-        SelectedTrack = track;
-        StateHasChanged();
+    // Controlled play-state inputs: the parent owns playback truth (the player service)
+    // and drives these. The gallery is presentational — it only matches by id to decide
+    // which card reflects the active state.
+    [Parameter] public TrackDto? ActiveTrack { get; set; }
+    [Parameter] public bool IsPlaying { get; set; }
+    [Parameter] public bool IsPaused { get; set; }
 
-        if (SelectedTrackChanged.HasDelegate)
-        {
-            await SelectedTrackChanged.InvokeAsync(track);
-        }
-    }
+    [Parameter] public EventCallback<TrackDto> OnPlay { get; set; }
+    [Parameter] public EventCallback<TrackDto> OnPause { get; set; }
+
+    private Task HandlePlayClick(TrackDto track) =>
+        OnPlay.HasDelegate ? OnPlay.InvokeAsync(track) : Task.CompletedTask;
+
+    private Task HandlePauseClick(TrackDto track) =>
+        OnPause.HasDelegate ? OnPause.InvokeAsync(track) : Task.CompletedTask;
 }