fix(ui): drawers close on any click outside the rail — TEST was the missing third

Creator: 'when the test slide-out is active, then any click off the div should
close the div — this behaviour applies to all tabs, not just TEST.'

MainWindow.Window_PreviewMouseLeftButtonDown already closed the Stream Settings
and YPP drawers on any click outside TextPullOutHost, but its close list skipped
TestSession — so the TEST drawer never dismissed on an outside click.

Fix: run TestSession.CloseDrawerCommand in the same outside-click branch.
All three drawers share the rail host, so the containment check is unchanged.

Good Dog: ONE integration test — the existing TestStream window section now
raises a window-root PreviewMouseLeftButtonDown (source = window => outside the
rail; deterministic, no OS mouse) and asserts the TEST and Stream Settings
drawers both close. Gate: clean build 0 warnings, full vstest 318/318.

ytLive.Tests/TestStreamTests.cs

@@ -6,6 +6,8 @@ using System.Net;
 using System.Net.Http;
 using System.Text;
 using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Input;
 using Microsoft.Data.Sqlite;
 using Xunit;
 using ytLive.Models;
@@ -183,6 +185,24 @@ public sealed class TestStreamTests
             Assert.True(model.TestSession.IsDrawerOpen);
             model.TestSession.CloseDrawerCommand.Execute(null);
             Assert.False(model.TestSession.IsDrawerOpen);
+
+            // Any left-click OUTSIDE the drawer rail collapses whichever drawer is
+            // open (MainWindow.Window_PreviewMouseLeftButtonDown) — the TEST drawer
+            // was the missing third; Stream Settings + YPP already behaved this way.
+            // A raised PreviewMouseLeftButtonDown on the window root lands "outside",
+            // deterministically, with no OS mouse input involved.
+            var outsideClick = new MouseButtonEventArgs(Mouse.PrimaryDevice, Environment.TickCount, MouseButton.Left)
+            {
+                RoutedEvent = UIElement.PreviewMouseLeftButtonDownEvent,
+            };
+            model.TestSession.ToggleDrawerCommand.Execute(null);
+            Assert.True(model.TestSession.IsDrawerOpen);
+            window.RaiseEvent(outsideClick);
+            Assert.False(model.TestSession.IsDrawerOpen, "TEST drawer must close on an outside click");
+            model.BroadcastForm.ToggleDrawerCommand.Execute(null);
+            Assert.True(model.BroadcastForm.IsDrawerOpen);
+            window.RaiseEvent(outsideClick);
+            Assert.False(model.BroadcastForm.IsDrawerOpen, "Stream Settings drawer must close on an outside click");
         }
         finally
         {