feat(cli): report a missing maigret in prism modules

[geoggrigori]

Summary

Closes #514. prism modules now says whether maigret, which runs as a separate program, can actually run.

Changes

• cli.py: a REQUIRED_BINARY table (maigret → maigret) and _find_maigret(), which resolves the binary the way modules/maigret_wrapper.py does: MAIGRET_BIN first, then the project's venv-maigret, then PATH via shutil.which. It only looks for the file and never runs it, so the listing stays instant.
• describe_modules() adds "requires": "maigret" and "found": true|false to modules that need an external program. Other rows are unchanged (the existing whois exact-match test still holds); blackbird gets nothing, since it is pure Python.
• Plain output, next to the key column:

$ python cli.py modules --type username
username
  blackbird
  maigret            program: maigret                     binary not found, skipped at scan time
  hudsonrock         HUDSONROCK_ENABLED                   required, not set, skipped at scan time

--json carries the same ("requires": "maigret", "found": false).

Type of change

• New feature

Testing

• New tests in tests/test_cli.py, patching shutil.which and the environment:
  • not found: plain output says "binary not found, skipped at scan time", and blackbird stays a bare line;
  • --json carries requires / found for maigret and nothing for blackbird;
  • found on PATH;
  • found through MAIGRET_BIN.
• pytest tests → 571 passed; flake8 with CI's critical selection is clean on the touched files.

🤖 Generated with Claude Code

https://claude.ai/code/session_01HbB5TeSB4kZHBYDnQaSmBS

[github-actions]

Thanks for the first pull request here. CI needs a maintainer to approve the run before it starts, so it may sit for a bit before anything happens. pytest tests/ -q passing is the main thing I look at.