Pre-existing test_orchestrator_skips_orphan_parquet_in_extracts caught
the regression: my filesystem fallback created master views for ANY
parquet on disk, including orphans where DELETE /api/admin/registry
removed the registry row but the parquet wasn't fully cleaned up.
Fix: load the set of registered materialized table_ids for THIS source
from table_registry before the scan, and skip any parquet whose stem
isn't in that set. If the registry read fails (test fixture, transient
DB error), skip the fallback entirely — orphan exposure is worse than
missing master view recovery.
Pre-existing test now passes. New regression test pins the orphan-skip
contract specifically for the filesystem-fallback path.
7781c3f331