fix: respect include patterns for directory symlinks

[Phoenix0531-sudo]

Summary

Fix a bug where directory symlinks bypass include-pattern filtering.

When a symlink points to a directory, Path.is_dir() follows the link and returns True. The _should_include() directory shortcut therefore accepted such symlinks before checking whether the symlink path matched the user's include patterns.

Root cause

src/gitingest/utils/ingestion_utils.py used this shortcut so normal directories are still traversed while looking for matching descendants:

if path.is_dir():
    return True

Because Path.is_dir() follows symlinks, a symlink pointing to a directory was treated like a regular directory and skipped the include-pattern match entirely.

Changes

• Added a not path.is_symlink() guard to _should_include()'s directory shortcut.
• Added a regression test covering a directory symlink whose own path does not match the include pattern.

Testing

• uv run pytest tests/test_ingestion.py::test_include_pattern_excludes_symlink_to_directory -v --tb=short
  • 1 passed, 110 warnings in 0.24s
• uv run pytest tests/test_ingestion.py -v --tb=short
  • 9 passed, 470 warnings in 0.33s
• uv run pytest tests/ -v --tb=short --ignore=tests/query_parser/test_git_host_agnostic.py
  • 140 passed, 63843 warnings in 165.57s (0:02:45)
• uv run --with ruff ruff check src/gitingest/utils/ingestion_utils.py tests/test_ingestion.py
  • All checks passed!

Note: a full local uv run pytest tests/ -v --tb=short run does not currently complete in my environment because tests/query_parser/test_git_host_agnostic.py hits an external Bitbucket repository that returns 403; I therefore ran the rest of the suite with that file ignored.

Related issue

Fixes #585