Initial commit: .NET MAUI Linux Platform

Complete Linux platform implementation for .NET MAUI with:

- 35+ Skia-rendered controls (Button, Label, Entry, CarouselView, etc.)
- Platform services (Clipboard, FilePicker, Notifications, DragDrop, etc.)
- Accessibility support (AT-SPI2, High Contrast)
- HiDPI and Input Method support
- 216 unit tests
- CI/CD workflows
- Project templates
- Documentation

🤖 Generated with Claude Code

Views/SkiaGraphicsView.cs

@@ -0,0 +1,65 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using SkiaSharp;
+using Microsoft.Maui.Graphics;
+using Microsoft.Maui.Graphics.Skia;
+
+namespace Microsoft.Maui.Platform;
+
+/// <summary>
+/// Skia-rendered graphics view that supports IDrawable for custom drawing.
+/// </summary>
+public class SkiaGraphicsView : SkiaView
+{
+    private IDrawable? _drawable;
+
+    public IDrawable? Drawable
+    {
+        get => _drawable;
+        set
+        {
+            _drawable = value;
+            Invalidate();
+        }
+    }
+
+    protected override void OnDraw(SKCanvas canvas, SKRect bounds)
+    {
+        // Draw background
+        if (BackgroundColor != SKColors.Transparent)
+        {
+            using var bgPaint = new SKPaint
+            {
+                Color = BackgroundColor,
+                Style = SKPaintStyle.Fill
+            };
+            canvas.DrawRect(bounds, bgPaint);
+        }
+
+        // Draw using IDrawable
+        if (_drawable != null)
+        {
+            var dirtyRect = new RectF(bounds.Left, bounds.Top, bounds.Width, bounds.Height);
+
+            using var skiaCanvas = new SkiaCanvas();
+            skiaCanvas.Canvas = canvas;
+
+            _drawable.Draw(skiaCanvas, dirtyRect);
+        }
+    }
+
+    protected override SKSize MeasureOverride(SKSize availableSize)
+    {
+        // Graphics view takes all available space by default
+        if (availableSize.Width < float.MaxValue && availableSize.Height < float.MaxValue)
+        {
+            return availableSize;
+        }
+
+        // Return a reasonable default size
+        return new SKSize(
+            availableSize.Width < float.MaxValue ? availableSize.Width : 100,
+            availableSize.Height < float.MaxValue ? availableSize.Height : 100);
+    }
+}