Verify Views files against decompiled, extract embedded types

Fixed files:
- SkiaImageButton.cs: Added SVG support with multi-path search
- SkiaNavigationPage.cs: Added LinuxApplication.IsGtkMode check
- SkiaRefreshView.cs: Added ICommand support (Command, CommandParameter)
- SkiaTemplatedView.cs: Added missing using statements

Extracted embedded types to separate files (matching decompiled pattern):
- From SkiaMenuBar.cs: MenuBarItem, MenuItem, SkiaMenuFlyout, MenuItemClickedEventArgs
- From SkiaNavigationPage.cs: NavigationEventArgs
- From SkiaTabbedPage.cs: TabItem
- From SkiaVisualStateManager.cs: SkiaVisualStateGroupList, SkiaVisualStateGroup, SkiaVisualState, SkiaVisualStateSetter
- From SkiaSwipeView.cs: SwipeItem, SwipeStartedEventArgs, SwipeEndedEventArgs
- From SkiaFlyoutPage.cs: FlyoutLayoutBehavior (already separate)
- From SkiaIndicatorView.cs: IndicatorShape (already separate)
- From SkiaBorder.cs: SkiaFrame
- From SkiaCarouselView.cs: PositionChangedEventArgs
- From SkiaCollectionView.cs: SkiaSelectionMode, ItemsLayoutOrientation
- From SkiaContentPresenter.cs: LayoutAlignment

Verified matching decompiled:
- SkiaContextMenu.cs, SkiaFlexLayout.cs, SkiaGraphicsView.cs

Build: 0 errors

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

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

Services/FontFallbackManager.cs

@@ -256,37 +256,6 @@ public class FontFallbackManager
     }
 }
 
-/// <summary>
-/// Represents a run of text with a specific typeface.
-/// </summary>
-public class TextRun
-{
-    /// <summary>
-    /// The text content of this run.
-    /// </summary>
-    public string Text { get; }
-
-    /// <summary>
-    /// The typeface to use for this run.
-    /// </summary>
-    public SKTypeface Typeface { get; }
-
-    /// <summary>
-    /// The starting character index in the original string.
-    /// </summary>
-    public int StartIndex { get; }
-
-    public TextRun(string text, SKTypeface typeface, int startIndex)
-    {
-        Text = text;
-        Typeface = typeface;
-        StartIndex = startIndex;
-    }
-}
-
-/// <summary>
-/// StringBuilder for internal use.
-/// </summary>
 file class StringBuilder
 {
     private readonly List<char> _chars = new();