fix: first native launch since refactor crashed — 3 stacked faults, all closed; RoundClip 'known failure' root-caused and green

User launch (2026-09-01 19:07) NRE'd in MainViewModel ctor:
1. SceneGraph (TASK 31) was 'null!'-declared, assigned mid-ctor, but Scenes is touched
   ~120 lines earlier — field-initialized now.
2. LeftPanel extraction (c9fd1bd) moved StaticResource users (EyeButton/EyeIconStyle)
   into a UserControl while the styles stayed window-scope — invisible at parse time;
   moved to Themes/Controls.xaml (app scope, the existing rule). Full audit: these were
   the only two offenders (grep of Controls/*.xaml StaticResource keys vs app dictionary).
3. RoundClipInteractionTests — the second 'known failure' the map never explained: it
   was two stale-test layers (window.FindName across the new UserControl namescope +
   VisualTreeHelper.HitTest, which returned the IsHitTestVisible=False WebViewHostPanel
   overlay for EVERY point; UIElement.InputHitTest — the real input pipeline — shows the
   corner IS grabbable in both Traditional and Round). Test fixed, no product bug.
Verified: clean rebuild 0 warnings; app boots (log shows full MainWindow loaded; user
clicked + closed, zero new exceptions; real DB Webcam row = the genuine C920, untouched);
RoundClip + 6 RealApp classes pass natively per-class.
Docs: ai.md known-failure note → 246/247 (audio only); TASK 31 verification paragraph
corrected ('cannot run headless' overstated — per-class Windows-host vstest runs them);
MyMistakes: InputHitTest-vs-VTH recipe + namescope/app-style + shared-log facts.
Spin-guard citations: WPF Visual Tree Overview (InputHitTest vs VisualTreeHelper hit
semantics) + XAML namescope docs, learn.microsoft.com.

Themes/Controls.xaml

@@ -66,6 +66,29 @@
         </Style.Triggers>
     </Style>
 
+    <!-- Eye icon: open when visible, slashed when hidden (source rows). App scope for
+         the same LeftPanel reason as EyeButton below. -->
+    <Style x:Key="EyeIconStyle" TargetType="Path">
+        <Setter Property="Data" Value="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5c-1.73,-4.39 -6,-7.5 -11,-7.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
+        <Style.Triggers>
+            <DataTrigger Binding="{Binding IsVisible}" Value="False">
+                <Setter Property="Data" Value="M12,7c2.76,0 5,2.24 5,5 0,0.65 -0.13,1.26 -0.36,1.83l2.92,2.92c1.51,-1.26 2.7,-2.89 3.43,-4.75 -1.73,-4.39 -6,-7.5 -11,-7.5 -1.4,0 -2.74,0.25 -3.98,0.7l2.16,2.16C10.74,7.13 11.35,7 12,7zM2,4.27l2.28,2.28 0.46,0.46C3.08,8.3 1.78,10.02 1,12c1.73,4.39 6,7.5 11,7.5 1.55,0 3.03,-0.3 4.38,-0.84l0.42,0.42L19.73,22 21,20.73 3.27,3 2,4.27zM7.53,9.8l1.55,1.55c-0.05,0.21 -0.08,0.43 -0.08,0.65 0,1.66 1.34,3 3,3 0.22,0 0.44,-0.03 0.65,-0.08l1.55,1.55c-0.67,0.33 -1.41,0.53 -2.2,0.53 -2.76,0 -5,-2.24 -5,-5 0,-0.79 0.2,-1.53 0.53,-2.2zM11.84,9.02l3.15,3.15 0.02,-0.16c0,-1.66 -1.34,-3 -3,-3l-0.17,0.01z"/>
+            </DataTrigger>
+        </Style.Triggers>
+    </Style>
+
+    <!-- Lives here (app scope), NOT in a window: Controls/LeftPanel.xaml references it
+         via StaticResource, and a UserControl cannot see window resources at parse
+         time (startup crash caught 2026-09-01). -->
+    <Style x:Key="EyeButton" TargetType="Button" BasedOn="{StaticResource IconButton}">
+        <Setter Property="ToolTip" Value="Hide Layer"/>
+        <Style.Triggers>
+            <DataTrigger Binding="{Binding IsVisible}" Value="False">
+                <Setter Property="ToolTip" Value="Show Layer"/>
+            </DataTrigger>
+        </Style.Triggers>
+    </Style>
+
     <Style x:Key="YtTextBox" TargetType="TextBox">
         <Setter Property="Background" Value="#0f3460"/>
         <Setter Property="Foreground" Value="#e0e0e0"/>