feat: Add virtual scroll support for modern web scraping

Add comprehensive virtual scroll handling to capture all content from pages that use DOM recycling techniques (Twitter, Instagram, etc).

Key features:
- New VirtualScrollConfig class for configuring virtual scroll behavior
- Automatic detection of three scrolling scenarios: no change, content appended, content replaced
- Intelligent HTML chunk capture and merging with deduplication
- 100% content capture from virtual scroll pages
- Seamless integration with existing extraction strategies
- JavaScript-based detection and capture for performance
- Tree-based DOM merging with text-based deduplication

Documentation:
- Comprehensive guide at docs/md_v2/advanced/virtual-scroll.md
- API reference updates in parameters.md and page-interaction.md
- Blog article explaining the solution and techniques
- Complete examples with local test server

Testing:
- Full test suite achieving 100% capture of 1000 items
- Examples for Twitter timeline, Instagram grid scenarios
- Local test server with different scrolling behaviors

This enables scraping of modern websites that were previously impossible to fully capture with traditional scrolling techniques.

mkdocs.yml

@@ -37,6 +37,7 @@ nav:
     - "Link & Media": "core/link-media.md"
   - Advanced:
     - "Overview": "advanced/advanced-features.md"
+    - "Virtual Scroll": "advanced/virtual-scroll.md"
     - "File Downloading": "advanced/file-downloading.md"
     - "Lazy Loading": "advanced/lazy-loading.md"
     - "Hooks & Auth": "advanced/hooks-auth.md"