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

tests/Views/SkiaRefreshViewTests.cs

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+// 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 Xunit;
+
+namespace Microsoft.Maui.Platform.Tests;
+
+public class SkiaRefreshViewTests
+{
+    [Fact]
+    public void Constructor_InitializesWithDefaultValues()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.False(refreshView.IsRefreshing);
+        Assert.Null(refreshView.Content);
+        Assert.True(refreshView.IsEnabled);
+    }
+
+    [Fact]
+    public void IsRefreshing_CanBeSet()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        refreshView.IsRefreshing = true;
+
+        Assert.True(refreshView.IsRefreshing);
+    }
+
+    [Fact]
+    public void Content_CanBeSet()
+    {
+        var refreshView = new SkiaRefreshView();
+        var content = new SkiaLabel { Text = "Test" };
+
+        refreshView.Content = content;
+
+        Assert.Equal(content, refreshView.Content);
+    }
+
+    [Fact]
+    public void Content_AddsChildToTree()
+    {
+        var refreshView = new SkiaRefreshView();
+        var content = new SkiaLabel { Text = "Test" };
+
+        refreshView.Content = content;
+
+        Assert.Equal(refreshView, content.Parent);
+    }
+
+    [Fact]
+    public void Content_RemovesPreviousChild()
+    {
+        var refreshView = new SkiaRefreshView();
+        var content1 = new SkiaLabel { Text = "First" };
+        var content2 = new SkiaLabel { Text = "Second" };
+
+        refreshView.Content = content1;
+        refreshView.Content = content2;
+
+        Assert.Null(content1.Parent);
+        Assert.Equal(refreshView, content2.Parent);
+    }
+
+    [Fact]
+    public void RefreshThreshold_DefaultValue()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.Equal(80f, refreshView.RefreshThreshold);
+    }
+
+    [Fact]
+    public void RefreshThreshold_CanBeSet()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        refreshView.RefreshThreshold = 100f;
+
+        Assert.Equal(100f, refreshView.RefreshThreshold);
+    }
+
+    [Fact]
+    public void RefreshColor_DefaultsToBlue()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.Equal(new SKColor(33, 150, 243), refreshView.RefreshColor);
+    }
+
+    [Fact]
+    public void RefreshColor_CanBeSet()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        refreshView.RefreshColor = SKColors.Red;
+
+        Assert.Equal(SKColors.Red, refreshView.RefreshColor);
+    }
+
+    [Fact]
+    public void RefreshBackgroundColor_DefaultsToWhite()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.Equal(SKColors.White, refreshView.RefreshBackgroundColor);
+    }
+
+    [Fact]
+    public void RefreshBackgroundColor_CanBeSet()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        refreshView.RefreshBackgroundColor = SKColors.LightGray;
+
+        Assert.Equal(SKColors.LightGray, refreshView.RefreshBackgroundColor);
+    }
+
+    [Fact]
+    public void RefreshingEvent_CanBeSubscribed()
+    {
+        var refreshView = new SkiaRefreshView();
+        bool eventRaised = false;
+
+        refreshView.Refreshing += (s, e) => eventRaised = true;
+
+        Assert.False(eventRaised); // Not raised yet
+    }
+
+    [Fact]
+    public void HitTest_ReturnsCorrectView()
+    {
+        var refreshView = new SkiaRefreshView();
+        var content = new SkiaLabel { Text = "Test" };
+        refreshView.Content = content;
+        refreshView.Arrange(new SKRect(0, 0, 200, 400));
+
+        var hit = refreshView.HitTest(100, 200);
+
+        Assert.NotNull(hit);
+    }
+
+    [Fact]
+    public void IsVisible_DefaultsToTrue()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.True(refreshView.IsVisible);
+    }
+
+    [Fact]
+    public void IsEnabled_DefaultsToTrue()
+    {
+        var refreshView = new SkiaRefreshView();
+
+        Assert.True(refreshView.IsEnabled);
+    }
+}