Remove duplicate CRC32 file and unused main_new.rs

- Delete src/crc32.rs (duplicate of src/hash/crc32.rs)
- Delete src/main_new.rs (unused file)
- All imports correctly reference src/hash/crc32::Crc32

Co-authored-by: lookbusy1344 <lookbusy1344@users.noreply.github.com>

Author: github-actions[bot]