fix: skip Unix permission test on Windows (#648)

[Stark-SK]

Summary

Skips test_persist_current_sets_0600_mode on Windows because Unix file permissions (0o600) are not supported on Windows.

Problem

On Windows, target.stat().st_mode & 0o777 returns 33206 (regular file), causing the assertion == 0o600 to fail. This blocks Windows contributors from running the test suite cleanly.

Fix

Added @pytest.mark.skipif(os.name == 'nt', ...) decorator to skip this test on Windows.

Testing

• uv run pytest tests/test_config_loader.py::test_persist_current_sets_0600_mode -v -> SKIPPED on Windows
• make check-all (ruff, mypy, pre-commit) passes

Fixes #648

[greptile-apps]

Greptile Summary

This PR skips a Unix-specific config loader test on native Windows. The main changes are:

• Added os for platform detection in tests/test_config_loader.py.
• Added a pytest skip marker to the 0o600 file mode test on Windows.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The skip condition matches the native Windows case that cannot support the Unix permission assertion.
• The test still runs on POSIX platforms.

Important Files Changed

Filename	Overview
tests/test_config_loader.py	Adds a Windows skip for the POSIX permission assertion and imports os for the skip condition.

_{Reviews (1): Last reviewed commit: "fix: skip Unix permission test on Window..." | Re-trigger Greptile}