Applies the same performance optimizations from v3.38.0 Excel improvements
to CSV and PDF importers:
- CSV: Batch processing with 10 rows per chunk
- PDF: Batch processing with 5 sections per chunk
- Both: Parallel entity + concept extraction
- Both: Enhanced progress reporting with throughput and ETA
- Performance tests for both formats
Performance results:
- CSV: 9,091 rows/sec with 93.8% cache hit rate
- PDF: 313 sections/sec with 90.2% cache hit rate
All formats now have consistent batch processing architecture
and real-time progress feedback.
