- Add type hints to _filter_computer_accounts and _dedup_netntlm_by_username
- Fix unclosed file handle when reading hash file for format detection
- Extract _count_computer_accounts helper to eliminate duplicate file reads
- Stream _filter_computer_accounts output instead of collecting in memory
- Only write .dedup file when duplicates actually exist
- Add tests for _count_computer_accounts, malformed lines, and no-file-on-zero-dupes
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>