Update sample webapp to mirror MAUI app features and structure

[Copilot]

This PR transforms the sample webapp to be a direct mirror of the MAUI app, implementing all the same features, pages, controls and functionality while using the shared Library project for business logic.

Changes Made

🎯 Core Requirements

• Direct Mirror: Webapp now has identical features, pages, controls and functionality as MAUI app
• Library Integration: Uses DeviceTestingKitApp.Library project for shared ViewModels and business logic
• Same Structure: Mirrors MainPage.xaml layout and component hierarchy exactly
• Identical Functionality: Counter behavior, display logic, and user interactions match perfectly

🔧 Technical Implementation

Project Dependencies

• Added reference to DeviceTestingKitApp.Library project
• Updated Program.cs with same service registration pattern as MauiProgram.cs

ViewModels Integration

• Uses MainViewModel and CounterViewModel from Library project
• Proper MVVM pattern with INotifyPropertyChanged support
• Same business logic and RelayCommand usage as MAUI app

Blazor Components

• Created CounterView.razor as Blazor equivalent of MAUI CounterView.xaml
• Implements same counter text logic: "Click me!" → "Clicked X time" → "Clicked X times"
• Proper data binding with property change notifications

Platform-Specific Services

• Implemented BlazorSemanticAnnouncer for web-specific accessibility
• Adapts ISemanticAnnouncer interface for web platform using JavaScript interop

UI Structure Updated Home.razor to mirror MainPage.xaml exactly:

• .NET bot image with same alt text
• "Hello, World!" heading with semantic styling
• "Welcome to .NET Multi-platform App UI" subheading
• Counter component with identical layout and behavior

🧪 Verification

• ✅ Solution builds successfully
• ✅ Webapp builds and runs without errors
• ✅ All dependencies resolved correctly
• ✅ Counter functionality works identically to MAUI app
• ✅ Uses shared Library project as required
• ✅ Maintains consistent MVVM architecture

The webapp is now a complete direct mirror of the MAUI app, sharing the same ViewModels and business logic while providing web-specific UI implementations.

Fixes #85.

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[Copilot]

This is ok, but we should copy the Maui way and have a razor class library for the Blazor things - just like we have a maui library for the Maui things.

Make sure we have the same sort of projects....

Created DeviceTestingKitApp.BlazorLibrary project that mirrors the MAUI library structure with the same folders: Controls/, Converters/, Features/. Moved all Blazor-specific components from the webapp to this new library and updated all references. The architecture now matches the MAUI pattern exactly. See commit 96f4a3c.