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.

docs/md_v2/advanced/lazy-loading.md

@@ -6,7 +6,7 @@ Many websites now load images **lazily** as you scroll. If you need to ensure th
 2. **`scan_full_page`** – Force the crawler to scroll the entire page, triggering lazy loads.  
 3. **`scroll_delay`** – Add small delays between scroll steps.  
 
-**Note**: If the site requires multiple “Load More” triggers or complex interactions, see the [Page Interaction docs](../core/page-interaction.md).
+**Note**: If the site requires multiple “Load More” triggers or complex interactions, see the [Page Interaction docs](../core/page-interaction.md). For sites with virtual scrolling (Twitter/Instagram style), see the [Virtual Scroll docs](virtual-scroll.md).
 
 ### Example: Ensuring Lazy Images Appear