Add two regression tests to tests/test_entities.py covering both save_entities paths (detected with day, attached with day=None). Each test loads to populate the loading cache, saves new entities, then loads again and asserts fresh data is returned. Both fail without the clear_entity_loading_cache() calls in saving.py (fix landed in a907ce41). Verifies VPE request req_hc5flgx4 — conftest.py autouse fixture and saving.py invalidation already landed in a907ce41; this adds the missing regression coverage so future reverts fail loudly.