New utility script:
- scripts/filter_user_csv.py - Filter DMR user database
- scripts/README.md - Documentation and usage examples
Features:
- Process full user database to extract US/Canada only
- Automatic statistics and file size reporting
- Can overwrite input or create new output file
- Preserves all CSV columns
Usage:
python3 scripts/filter_user_csv.py user_full.csv user.csv
Benefits:
- Reproducible filtering for future database updates
- Clear documentation for maintenance
- Easy to add more countries if needed
