Mouse highlighter: support a spotlight mode - inner transparent, out a backdrop (#40043)

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https://github.com/user-attachments/assets/0748c526-fcf5-4859-b832-14a413d2cad1

src/settings-ui/Settings.UI.Library/MouseHighlighterProperties.cs

@@ -41,6 +41,9 @@ namespace Microsoft.PowerToys.Settings.UI.Library
         [JsonPropertyName("auto_activate")]
         public BoolProperty AutoActivate { get; set; }
 
+        [JsonPropertyName("spotlight_mode")]
+        public BoolProperty SpotlightMode { get; set; }
+
         public MouseHighlighterProperties()
         {
             ActivationShortcut = DefaultActivationShortcut;
@@ -52,6 +55,7 @@ namespace Microsoft.PowerToys.Settings.UI.Library
             HighlightFadeDelayMs = new IntProperty(500);
             HighlightFadeDurationMs = new IntProperty(250);
             AutoActivate = new BoolProperty(false);
+            SpotlightMode = new BoolProperty(false);
         }
     }
 }