Social bar (Branch B): global resource with per-scene presence — Models/Socials.cs (19 services, icons, canonical URLs), Services/SocialValidator.cs (HTTP lookup validation seam), LayoutStore schema v7 (Socials + SocialEntry tables + Scene.HasSocialBar), MainViewModel (socials collection, AddSocial/RemoveSocial/ToggleSceneSocialBar commands, freemium cap YT+1, premium seam), MainWindow.xaml (footer Social button + [+/-] toggle on meter line, preview bar rendering top/bottom + LCR), 4 integration tests (roundtrip, empty-not-persisted, canonical URLs, icons), 85 tests passing, 0 warnings

Models/Scene.cs

@@ -12,6 +12,7 @@ public class Scene : INotifyPropertyChanged
     private bool _isEditing;
     private bool _isHidden;
     private bool _hasBackdrop;
+    private bool _hasSocialBar;
 
     public string Name
     {
@@ -41,6 +42,16 @@ public class Scene : INotifyPropertyChanged
         set => Set(ref _hasBackdrop, value);
     }
 
+    /// <summary>
+    /// Whether the social bar plays on this scene. Toggled by the footer [+]/[-]
+    /// control — the socials themselves are a global resource (see SocialsConfig).
+    /// </summary>
+    public bool HasSocialBar
+    {
+        get => _hasSocialBar;
+        set => Set(ref _hasSocialBar, value);
+    }
+
     /// <summary>
     /// The scene's rendered elements in z-order (back to front): multi-instance
     /// Sources plus this scene's webcam usage (<see cref="WebcamConfig"/>), if any.