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/AudioPlayerBar.razor

@@ -25,6 +25,9 @@ else
                                          HasPrevious="HasPrevious"
                                          SkipNext="@SkipNext"
                                          SkipPrevious="@SkipPrevious"
+                                         ShowQueueButton="ShowQueueButton"
+                                         QueueOpen="_queueOpen"
+                                         QueueToggle="@ToggleQueue"
                                          Class="transport-zone"/>
 
                     <VolumeZone Volume="@Volume" VolumeChanged="@OnVolumeChange"/>
@@ -49,12 +52,27 @@ else
             
         @if (!string.IsNullOrEmpty(ErrorMessage))
         {
-            <MudAlert Severity="Severity.Error" 
-                      ShowCloseIcon="true" 
-                      CloseIconClicked="ClearError" 
+            <MudAlert Severity="Severity.Error"
+                      ShowCloseIcon="true"
+                      CloseIconClicked="ClearError"
                       Class="ma-2">
                 @ErrorMessage
             </MudAlert>
         }
+
+        @* Docked queue overlay (Phase 17 §3.2). MudOverlay portals to the body, so its position here in
+           the dock subtree does not affect its screen-centered rendering. Only mounted in docked mode —
+           the Fixed embed gets its own inline panel in a later wave. *@
+        @if (ShowQueueButton)
+        {
+            <QueueOverlay Visible="_queueOpen"
+                          Items="QueueItems"
+                          CurrentIndex="QueueCurrentIndex"
+                          OnClose="@CloseQueue"
+                          OnClear="@ClearUpcoming"
+                          OnReorder="@OnQueueReorder"
+                          OnRemove="@OnQueueRemove"
+                          OnJump="@OnQueueJump"/>
+        }
     </div>
 }