chore: improve vulture maintenance path

[lphuc2250gma]

Summary:

• Add precise type annotations to the small helper functions in vulture/utils.py (e.g. format_path, condition_is_always_false/true helpers) and add a focused unit test in tests/test_utils.py covering an edge case in format_path (e.g. paths outside cwd, absolute paths on different platforms) — a narrow, mechanical change confined to one small module plus one test file.
• Keep the change narrow so it is straightforward to review.

Notes:

• I kept this scoped to the relevant implementation and tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.46%. Comparing base (81fb2ac) to head (1c58f88).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #418   +/-   ##
=======================================
  Coverage   93.46%   93.46%           
=======================================
  Files           9        9           
  Lines         597      597           
=======================================
  Hits          558      558           
  Misses         39       39           

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