Add Windows platform support to Plugin.Maui.ZoomView

[Copilot]

This PR extends the Plugin.Maui.ZoomView library to support the Windows (WinUI) platform, enabling ZoomView to work on Windows in addition to Android and iOS.

Changes Made

🪟 Windows Platform Implementation

• Added Platforms/Windows/PlatformZoomView.cs: Windows-specific zoom view using WinUI ScrollViewer with native zoom capabilities
• Added Platforms/Windows/ZoomViewHandler.cs: Windows-specific handler implementation following the MAUI Handler pattern
• Enhanced zoom features: Smooth animations, dynamic zoom bounds, improved double-tap handling with float tolerance

📦 Project Configuration Updates

• Updated target frameworks: Added net9.0-windows10.0.19041.0 to both main project and sample app
• Added conditional compilation: Windows platform files are properly excluded/included based on target framework
• Updated package metadata: Description and tags now include Windows platform support

📖 Documentation & Testing

• Updated README.md: Added Windows to supported platforms table and included platform implementation details
• API validation: Created and ran tests to ensure no breaking changes to existing API
• Backward compatibility: All existing Android and iOS functionality remains unchanged

Implementation Details

The Windows implementation leverages WinUI's native ScrollViewer control which provides:

• ✅ Pinch-to-zoom gestures
• ✅ Pan/scroll when zoomed in
• ✅ Mouse wheel zoom support
• ✅ Double-tap zoom in/out (configurable via ZoomInOnDoubleTap/ZoomOutOnDoubleTap)
• ✅ Reset to original zoom and position
• ✅ Smooth animations and inertia

Platform Support Matrix

Platform	Status	Implementation
🤖 Android	✅ Supported	Custom Matrix transformations
🍎 iOS	✅ Supported	Native UIScrollView
🪟 Windows	✅ NEW	Native WinUI ScrollViewer

Usage Example

The Windows implementation works seamlessly with the existing API:

<ContentPage xmlns:zoomview="clr-namespace:Plugin.Maui.ZoomView;assembly=Plugin.Maui.ZoomView">
    <zoomview:ZoomView>
        <Image Source="myimage.jpg" />
    </zoomview:ZoomView>
</ContentPage>

No code changes required - existing MAUI applications targeting Windows will automatically gain zoom functionality when this update is applied.

Fixes #11.

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