Implement file deduplication at scale

Implement a command-line tool to find duplicate files in a directory tree. Use OS/pathlib primitives to recursively enumerate files. Apply prefilters (e.g., group by file size and/or first N bytes) to narrow candidates, then confirm duplicates with a strong hash (chunked for large files). Discuss handling of large files, memory and I/O trade-offs, symlinks and permissions, error cases, and how to output groups of duplicates with options to hard-link, move, or delete. Analyze time and space complexity.