<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Improvements**
- Increased the default concurrency for background tasks, enhancing processing efficiency.
- Improved handling of empty or unsupported documents to ensure consistent processing.
- Optimized document filtering to exclude certain documents from processing, improving performance.
- **Bug Fixes**
- Enhanced detection of empty document summaries, reducing errors during processing.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->