Closes: [BS-2578](https://linear.app/affine-design/issue/BS-2578/优化-footnote-预览的逻辑：支持缓存结果，避免重复-loading)
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Introduced a link preview caching mechanism, enabling faster and more efficient reuse of link preview data across the app.
- Added a feature flag for enabling or disabling link preview cache, configurable through workspace experimental settings.
- Enhanced localization with new entries describing the link preview cache feature.
- **Improvements**
- Updated link preview service architecture for better extensibility and maintainability.
- Improved integration of feature flags throughout chat and rendering components.
- **Bug Fixes**
- Fixed tooltip formatting for footnote URLs.
- **Chores**
- Updated dependencies and localization completeness tracking.
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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Refactor**
- Unified internal data access by replacing all references from `doc` to `store` across all components, blocks, widgets, and utilities. This affects how readonly state, block operations, and service retrieval are handled throughout the application.
- **Tests**
- Updated all test utilities and test cases to use `store` instead of `doc` for document-related operations.
- **Chores**
- Updated context providers and property names to reflect the change from `doc` to `store` for improved consistency and maintainability.
No user-facing features or behaviors have changed.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
donteatfriedrice