fix: preserve inverted gitignore traversal

[shixi-li]

Fixes #225.

Summary

Inverted .gitignore files that start with * and reopen directories with !*/ are pruned under pathspec 1.x, so source files below those directories never reach the matcher.

• constrain pathspec to the last compatible 0.x line and refresh uv.lock
• add a real tree-walk regression for root and nested C/C++ source files
• verify ordinary ignored files and later Content/ exclusions remain excluded

The dependency bound is intentional: GitIgnoreSpec in pathspec 1.0.4 and 1.1.1 marks the reopened directories ignored, while 0.12.1 matches Git for this pattern. Using plain PathSpec is not equivalent because it changes file-ignore behavior.

Testing

• uv run pytest tests/test_file_walk.py -v
• uv run mypy src/ tests/
• uv run prek run --all-files --verbose --show-diff-on-failure --skip pytest
• uv run pytest tests/ -v (270 passed, 8 deselected)

[badmonster0]

thanks a lot for the PR! @georgeh0 can help take a look!

[georgeh0]

Thanks!