Unit tests for `detect_username_hash_format`: per-mode positives
(MD5/SHA1/SHA256/SHA512/NTLM/LM), negatives (bare hash, wrong hex
length, non-hex, mixed valid/invalid, pwdump, trailing garbage),
blocklist modes, unknown modes, and file-handling (BOM, CRLF, null
bytes, unicode username, comments, blank lines, missing/empty file,
sample_size).
Integration tests for the injection flow: asserts `--username` appears
in the command emitted by `hcatBruteForce` when `hcatUsernamePrefix` is
set, asserts no duplicate when `hcatTuning` already includes
`--username`, and verifies `_append_potfile_arg` still injects the flag
even when called with `use_potfile_path=False`.
Refs #107
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
