Closes: [BS-3439](https://linear.app/affine-design/issue/BS-3439/pdf-独立页面split-view-中的-status-组件)
Related to: [BS-3143](https://linear.app/affine-design/issue/BS-3143/更新-loading-和错误样式)
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Added a dedicated error handling and reload interface for PDF attachments, allowing users to retry loading PDFs when errors occur.
- **Refactor**
- Improved PDF viewer interface with clearer loading and error states.
- Enhanced attachment type detection for better performance and maintainability.
- Streamlined attachment preview logic for more direct and efficient model retrieval.
- Simplified internal PDF metadata handling and control flow for improved clarity.
- Clarified conditional rendering logic in attachment viewer components.
- Introduced explicit loading state management and refined rendering logic in attachment pages.
- **Style**
- Updated and added styles for PDF viewer controls and error status display.
- **Tests**
- Added end-to-end tests validating PDF preview error handling and attachment not-found scenarios.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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