docs: add WebView2 package reference documentation

[woeoio]

🚀 PR Summary: Add Comprehensive WebView2 Package Documentation

📚 What's New

This PR introduces a complete documentation suite for the twinBASIC WebView2 Package, enabling developers to embed modern web content using Microsoft Edge WebView2 controls.

📁 Documentation Structure (17 Files)

Category	Files
📑 Package Index	PackageReference/index.md (updated) ⭐
🏠 WebView2 Overview	Webview2/index.md, Webview2/README.md
🚀 Getting Started	Webview2/Getting-started.md
🎛️ Core API Reference	Webview2/WebView2.md, Webview2/WebView2-Events.md, Webview2/WebView2-Methods.md, Webview2/WebView2-Properties.md
⚙️ Configuration	Webview2/WebView2EnvironmentOptions.md
🌐 HTTP Handling	Webview2/WebView2Request.md, Webview2/WebView2Response.md, Webview2/WebView2RequestHeaders.md, Webview2/WebView2ResponseHeaders.md, Webview2/WebView2HeadersCollection.md, Webview2/WebView2Header.md
🔢 Enumerations	Webview2/WebView2-Enumerations.md
⚡ Advanced Topics	Webview2/DeferredCallback.md

🆕 Changes Overview

1️⃣ Package Reference Index (PackageReference/index.md)

| Package | Description |
|---------|-------------|
| [WebView2](./Webview2/) | Microsoft Edge WebView2 control for embedding web content |

• ✅ Added WebView2 package entry to the Package Reference section

2️⃣ WebView2 Documentation Suite (PackageReference/Webview2/)

• 16 comprehensive markdown files covering all aspects of WebView2 integration

✨ Key Features Documented

• 🌍 Web Content Display - Load URLs, HTML strings, virtual host mapping
• 🧭 Navigation Control - Back/forward, refresh, custom HTTP requests
• 💬 JavaScript Integration - Bidirectional communication, sync/async JS calls
• 🔗 Object Sharing - Expose COM objects to JavaScript with deferred invocation
• 🎯 Event Handling - 20+ events including lifecycle, navigation, permissions
• 🛠️ Advanced Features - DevTools, PDF export, download manager, audio control

📋 Requirements

• Windows 7 SP1+ / Windows 10/11
• WebView2 Runtime (Evergreen) 86.0.616.0+

---

📝 Total: +17 new files | ~150KB of comprehensive documentation | Ready for review! 🎉

[woeoio]

Fix broken internal links in WebView2 documentation

• Fix incorrect file references:

  • ./Enumerations.md -> ./WebView2-Enumerations.md
  • Remove link to non-existent Re-entrancy.md
  • Remove link to non-existent Customize-the-UserDataFolder.md

• Fix incorrect anchor links in README.md:

  • #javascript-interaction-methods -> #javascript-interaction
  • #message-passing-methods -> #javascript-interaction
  • #web-resource-interception-methods -> #resource-management
  • #advanced-features-methods -> #advanced-features

• Fix anchor link in WebView2-Methods.md:

  • #addobject-deferred-invocation -> #deferred-invocation-for-addobject

Fixes HTML-Proofer validation errors in CI build

[woeoio]