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.

DeepDrftTests/QueueServiceTests.cs

@@ -678,6 +678,75 @@ public class QueueServiceTests
         });
     }
 
+    // --- ClearUpcoming (OQ5: keep the current track, drop the up-next) — Phase 17 wave 17.2 ---
+
+    [Test]
+    public async Task ClearUpcoming_KeepsCurrentTrack_DropsTheRest_WithoutStopping()
+    {
+        // Current = track-2; ClearUpcoming leaves only track-2 at index 0 and does not stop the player.
+        await _queue.PlayRelease(Tracks(4), startIndex: 1);
+        var streamedBefore = _player.SelectedTracks.Count;
+
+        _queue.ClearUpcoming();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(_queue.Items.Select(t => t.EntryKey), Is.EqualTo(new[] { "track-2" }));
+            Assert.That(_queue.CurrentIndex, Is.EqualTo(0));
+            Assert.That(_queue.Current!.EntryKey, Is.EqualTo("track-2"));
+            Assert.That(_queue.HasNext, Is.False);
+            Assert.That(_queue.HasPrevious, Is.False);
+            Assert.That(_player.StopCount, Is.EqualTo(0), "ClearUpcoming must not stop playback (C2)");
+            Assert.That(_player.SelectedTracks, Has.Count.EqualTo(streamedBefore),
+                "ClearUpcoming must not re-stream");
+        });
+    }
+
+    [Test]
+    public async Task ClearUpcoming_RaisesQueueChangedOnce()
+    {
+        await _queue.PlayRelease(Tracks(3));
+        var changed = 0;
+        _queue.QueueChanged += () => changed++;
+
+        _queue.ClearUpcoming();
+
+        Assert.That(changed, Is.EqualTo(1));
+    }
+
+    [Test]
+    public async Task ClearUpcoming_WhenOnlyCurrentRemains_IsNoOpAndDoesNotRaiseQueueChanged()
+    {
+        await _queue.PlayRelease(Tracks(1));
+        var raised = false;
+        _queue.QueueChanged += () => raised = true;
+
+        _queue.ClearUpcoming();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(_queue.Items, Has.Count.EqualTo(1));
+            Assert.That(_queue.CurrentIndex, Is.EqualTo(0));
+            Assert.That(raised, Is.False);
+        });
+    }
+
+    [Test]
+    public void ClearUpcoming_OnEmptyQueue_IsNoOpAndDoesNotRaiseQueueChanged()
+    {
+        var raised = false;
+        _queue.QueueChanged += () => raised = true;
+
+        _queue.ClearUpcoming();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(_queue.Items, Is.Empty);
+            Assert.That(_queue.CurrentIndex, Is.EqualTo(-1));
+            Assert.That(raised, Is.False);
+        });
+    }
+
     // --- QueueChanged notifications ---
 
     [Test]