fix: anchor kind discovery to project root (#4763)

[Jkhall81]

Summary

This PR fixes a bug where files were misidentified as tasks if the project was located inside a parent directory named tasks.

By anchoring the file discovery logic to the project root, the linter now performs glob matching against paths relative to the project directory. This prevents parent folder names from leaking into the kind identification process.

Changes

• Modified kind_from_path to relativize file paths against the project root before matching against DEFAULT_KINDS.
• Added a fallback to absolute paths for standalone files outside of a recognized project.
• Added regression tests in test_file_utils.py covering nested parent directories and standard task discovery.

Fixes #4763