The test was using tmp.withDir which tries to clean up the temp directory
after the callback returns. However, with AVA, the tests are only REGISTERED
in the callback - they run asynchronously AFTER the callback returns.

This caused race conditions:
- Windows: EBUSY (files still locked by npm/pnpm processes)
- Linux: ENOTEMPTY (files created by tests still exist)

Changed to tmp.dir() without automatic cleanup. Temp directories are
cleaned by the OS periodically anyway.