Add Long Animation Frames Script Attribution snippet

- New comprehensive snippet for analyzing script attribution in LoAF
- Reusable function with configurable duration parameter (default: 10s)
- Automatic categorization by script origin (first-party, framework, third-party, extensions)
- Visual ASCII charts showing blocking time breakdown by category
- Top 10 blocking scripts with function-level details
- RUM-ready data export structure
- Browser support check with helpful error messages
- Mermaid diagram showing analysis workflow
- Complete documentation with real-world examples and integration tips
- Quick tips section explaining custom duration usage

Author: nucliweb