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.

TASKS.md

@@ -61,6 +61,7 @@
 | 43 | Native events & alerts: chat parity (all six event types + server poll cadence) + six-animation native alert box | ✅ Done (2026-09-24) | [`TASKS/task-43-native-alerts.md`](TASKS/task-43-native-alerts.md) |
 | 44 | TEST-tab chat fix: resolve liveChatId from snippet (not contentDetails) + poll until the broadcast is live | ✅ Done (2026-09-25); full suite 318/318 | [`TASKS/task-44-test-chat-fix.md`](TASKS/task-44-test-chat-fix.md) |
 | 45 | TEST-tab chat fix #2: insert body must declare `snippet.type` (400 MISSING_REQUIRED_FIELD) | ✅ Done (2026-09-25) | [`TASKS/task-45-chat-insert-type.md`](TASKS/task-45-chat-insert-type.md) |
+| 46 | Drawers: click outside the rail closes whichever is open — TEST added to the existing Stream Settings + YPP dismiss behavior | ✅ Done (2026-09-25) | [`TASKS/task-46-drawer-click-outside-close.md`](TASKS/task-46-drawer-click-outside-close.md) |
 
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