Fix handlers to match decompiled production code

- ButtonHandler: Removed MapText/TextColor/Font (not in production), fixed namespace
- LabelHandler: Added CharacterSpacing/LayoutAlignment/FormattedText, ConnectHandler gesture logic
- EntryHandler: Added CharacterSpacing/ClearButtonVisibility/VerticalTextAlignment
- EditorHandler: Created from decompiled (was missing)
- SliderHandler: Fixed namespace, added ConnectHandler init calls
- SwitchHandler: Added OffTrackColor logic, fixed namespace
- CheckBoxHandler: Added VerticalLayoutAlignment/HorizontalLayoutAlignment
- ProgressBarHandler: Added ConnectHandler/DisconnectHandler IsVisible tracking
- PickerHandler: Created from decompiled with collection changed tracking
- ActivityIndicatorHandler: Removed IsEnabled/BackgroundColor (not in production)
- All handlers now use namespace Microsoft.Maui.Platform.Linux.Handlers
- All handlers have proper null checks on PlatformView
- Updated MERGE_TRACKING.md with accurate status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Types/ToggledEventArgs.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Maui.Platform;
+
+public class ToggledEventArgs : EventArgs
+{
+    public bool Value { get; }
+
+    public ToggledEventArgs(bool value)
+    {
+        Value = value;
+    }
+}