Add control gallery sample and roadmap documentation

- Add comprehensive ControlGallery sample app with 12 pages
  demonstrating all 35+ controls
- Add detailed ROADMAP.md with version milestones
- Add README placeholders for VSIX icons and template images
- Sample pages include: Home, Buttons, Labels, Entry, Pickers,
  Sliders, Toggles, Progress, Images, CollectionView, CarouselView,
  SwipeView, RefreshView

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

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

samples/ControlGallery/Pages/RefreshViewPage.xaml.cs

@@ -0,0 +1,48 @@
+namespace ControlGallery.Pages;
+
+public partial class RefreshViewPage : ContentPage
+{
+    private readonly Random _random = new();
+    private readonly string[] _headlines = new[]
+    {
+        "OpenMaui 1.0 Released!",
+        "Linux Desktop Apps Made Easy",
+        "SkiaSharp Powers Modern UIs",
+        "Cross-Platform Development Grows",
+        ".NET 9 Performance Boost",
+        "XAML Hot Reload Coming Soon",
+        "Wayland Support Expanding",
+        "Community Contributions Welcome",
+        "New Controls Added Weekly",
+        "Accessibility Features Improved"
+    };
+
+    public RefreshViewPage()
+    {
+        InitializeComponent();
+        UpdateNews();
+    }
+
+    private async void OnRefreshing(object sender, EventArgs e)
+    {
+        // Simulate network delay
+        await Task.Delay(1500);
+
+        UpdateNews();
+        LastRefreshLabel.Text = $"Last refreshed: {DateTime.Now:HH:mm:ss}";
+
+        RefreshContainer.IsRefreshing = false;
+    }
+
+    private void OnManualRefreshClicked(object sender, EventArgs e)
+    {
+        RefreshContainer.IsRefreshing = true;
+    }
+
+    private void UpdateNews()
+    {
+        NewsItem1.Text = _headlines[_random.Next(_headlines.Length)];
+        NewsItem2.Text = _headlines[_random.Next(_headlines.Length)];
+        NewsItem3.Text = _headlines[_random.Next(_headlines.Length)];
+    }
+}