Closes: [BS-3302](https://linear.app/affine-design/issue/BS-3302/處理-affine-中的-redos-風險)
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## Summary by CodeRabbit
- **Bug Fixes**
- Improved handling of footnote definitions with varied spacing, special characters, and malformed or incomplete entries, ensuring more reliable processing and display.
- **New Features**
- Introduced advanced parsing for footnote URLs to improve accuracy and validation of footnote content.
- **Tests**
- Expanded test coverage for footnote processing to include additional edge cases and mixed content scenarios, enhancing overall robustness.
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## Summary by CodeRabbit
- **New Features**
- Images and icons in bookmark cards are now loaded through an image proxy for improved reliability and consistency.
- Embed blocks for GitHub, Loom, and YouTube now display banner and creator images via an image proxy service for enhanced image loading.
- **Refactor**
- Simplified backend URL handling and proxy logic for images, resulting in more efficient processing and reduced complexity.
- Consolidated image proxy middleware and services into a shared adapter module for streamlined imports and improved maintainability.
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Closes: [BS-3272](https://linear.app/affine-design/issue/BS-3272/footnote-适配-exa-api-返回结果)
## What's Changed
Add link preview data support (favicon, title, description) for URL references in footnotes:
- Store and display URL preview data in footnotes
- Add encoding/decoding support for favicon URLs
- Optimize link preview by using existing preview data when available
donteatfriedrice