Add DialogsPage and MoreControlsPage to ShellDemo

DialogsPage demonstrates:
- Alert dialogs (simple, confirmation)
- Action sheets (with destructive option)
- Input prompts (text, numeric)
- File pickers (single, multiple, images)
- Folder picker

MoreControlsPage demonstrates:
- Stepper (basic and custom range)
- RadioButton (vertical and horizontal groups)
- Image placeholders with aspect modes
- Clipboard (copy/paste)
- Share and Launcher services
- BoxView shapes and dividers

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

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

samples/ShellDemo/Pages/MoreControlsPage.xaml.cs

@@ -0,0 +1,131 @@
+using System;
+using Microsoft.Maui.ApplicationModel;
+using Microsoft.Maui.ApplicationModel.DataTransfer;
+using Microsoft.Maui.Controls;
+
+namespace ShellDemo.Pages;
+
+public partial class MoreControlsPage : ContentPage
+{
+    private int _eventCount = 0;
+
+    public MoreControlsPage()
+    {
+        InitializeComponent();
+    }
+
+    private void LogEvent(string message)
+    {
+        _eventCount++;
+        var timestamp = DateTime.Now.ToString("HH:mm:ss");
+        EventLog.Text = $"[{timestamp}] {_eventCount}. {message}\n{EventLog.Text}";
+    }
+
+    // Stepper
+    private void OnStepperChanged(object? sender, ValueChangedEventArgs e)
+    {
+        StepperValueLabel.Text = $"Value: {(int)e.NewValue}";
+        LogEvent($"Stepper: {(int)e.NewValue}");
+    }
+
+    private void OnCustomStepperChanged(object? sender, ValueChangedEventArgs e)
+    {
+        CustomStepperLabel.Text = $"Value: {(int)e.NewValue}";
+        LogEvent($"Custom Stepper: {(int)e.NewValue}");
+    }
+
+    // RadioButton
+    private void OnRadioChanged(object? sender, CheckedChangedEventArgs e)
+    {
+        if (e.Value && sender is RadioButton rb)
+        {
+            RadioResultLabel.Text = $"Selected: {rb.Content}";
+            LogEvent($"Size: {rb.Content}");
+        }
+    }
+
+    private void OnColorRadioChanged(object? sender, CheckedChangedEventArgs e)
+    {
+        if (e.Value && sender is RadioButton rb)
+        {
+            LogEvent($"Color: {rb.Content}");
+        }
+    }
+
+    // Clipboard
+    private async void OnCopyClicked(object? sender, EventArgs e)
+    {
+        var text = ClipboardEntry.Text;
+        if (!string.IsNullOrEmpty(text))
+        {
+            await Clipboard.Default.SetTextAsync(text);
+            ClipboardResultLabel.Text = $"Copied: {text}";
+            LogEvent($"Copied to clipboard: {text}");
+        }
+        else
+        {
+            ClipboardResultLabel.Text = "Nothing to copy";
+            LogEvent("Copy failed: empty text");
+        }
+    }
+
+    private async void OnPasteClicked(object? sender, EventArgs e)
+    {
+        if (Clipboard.Default.HasText)
+        {
+            var text = await Clipboard.Default.GetTextAsync();
+            ClipboardEntry.Text = text;
+            ClipboardResultLabel.Text = $"Pasted: {text}";
+            LogEvent($"Pasted from clipboard: {text}");
+        }
+        else
+        {
+            ClipboardResultLabel.Text = "Clipboard is empty";
+            LogEvent("Paste failed: clipboard empty");
+        }
+    }
+
+    // Share & Launcher
+    private async void OnShareTextClicked(object? sender, EventArgs e)
+    {
+        try
+        {
+            await Share.Default.RequestAsync(new ShareTextRequest
+            {
+                Text = "Check out OpenMaui Linux - .NET MAUI for Linux!",
+                Title = "Share OpenMaui"
+            });
+            LogEvent("Share dialog opened");
+        }
+        catch (Exception ex)
+        {
+            LogEvent($"Share error: {ex.Message}");
+        }
+    }
+
+    private async void OnOpenUrlClicked(object? sender, EventArgs e)
+    {
+        try
+        {
+            await Launcher.Default.OpenAsync("https://github.com/pablotoledo/OpenMaui-Linux");
+            LogEvent("Opened URL in browser");
+        }
+        catch (Exception ex)
+        {
+            LogEvent($"Launcher error: {ex.Message}");
+        }
+    }
+
+    private async void OnOpenEmailClicked(object? sender, EventArgs e)
+    {
+        try
+        {
+            await Launcher.Default.OpenAsync("mailto:info@example.com?subject=OpenMaui%20Feedback");
+            LogEvent("Opened email client");
+        }
+        catch (Exception ex)
+        {
+            LogEvent($"Email error: {ex.Message}");
+        }
+    }
+}