fix(ingestor): bare except Exception around update_residency_region reclassifies all exceptions as DependencyUnavailable 503 #290

Summary

The try/except Exception block around update_residency_region in ingestor.py (lines ~236-253) unconditionally converts any exception type to DependencyUnavailable(503). If update_residency_region raises a ProblemException (typed 409/404), the bare except converts it to a generic 503, destroying the original status code.

Root cause

Fix #266 replaced the silent pass with a proper except Exception that logs and raises DependencyUnavailable. But it uses bare Exception which is too broad.

Fix

backend/app/adapters/ingestor.py lines ~236-253: narrow the except to the actually expected types (SQLAlchemyError, ConnectionError, IOError), and let ProblemException or other typed exceptions propagate naturally.

Impact

Any typed exception from update_residency_region (including valid conflict/not-found errors) is silently misclassified as a 503 availability error, making diagnosis impossible.