feat(player): docked queue overlay with reorder, remove, jump, and clear-upcoming

Add a Queue toggle to the docked player bar opening a centered editable queue
overlay. New additive QueueService.ClearUpcoming keeps the playing track while
dropping the rest. Current track is non-removable.

DeepDrftPublic.Client/Controls/AudioPlayerBar/PlayerTransportZone.razor.cs

@@ -18,5 +18,15 @@ public partial class PlayerTransportZone : ComponentBase
     [Parameter] public bool HasPrevious { get; set; }
     [Parameter] public EventCallback SkipNext { get; set; }
     [Parameter] public EventCallback SkipPrevious { get; set; }
+
+    /// <summary>Whether to render the Queue toggle button. Gated on a non-empty queue by the bar.</summary>
+    [Parameter] public bool ShowQueueButton { get; set; }
+
+    /// <summary>Whether the queue overlay is open. Drives the button's active state.</summary>
+    [Parameter] public bool QueueOpen { get; set; }
+
+    /// <summary>Raised when the Queue button is clicked. The bar toggles the overlay.</summary>
+    [Parameter] public EventCallback QueueToggle { get; set; }
+
     [Parameter] public string? Class { get; set; }
 }