Several tests force a failure with chmod (0o555 directory, 0o000 file) or
assert exact 0o600/0o755 mode bits. NTFS has no POSIX modes: chmod on a
directory is a no-op, a file cannot be made unreadable, and stat reports
0o666. The write these tests expect to fail succeeds, so the assertion
inverts. Skip them where the host is Windows; the win32 code paths under
test already bypass the mode check.

Also skip the RotatingFileSink over-long-name test there, where the OS
reports ENOENT rather than ENAMETOOLONG and the sink's missing-file
handling is what runs.

Co-Authored-By: Claude Code <noreply@anthropic.com>