CI runs pytest without root, so the new /var/lib/romm/sync default
fails when FSSyncHandler tries to mkdir its base path at import time.
The other handlers stay writable in tests because they derive from
ROMM_BASE_PATH=romm_test (relative); pin SYNC_BASE_PATH the same way.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>