* fix: custom pg schema is not reliable
* fix
* fix
* fix: WorkerPoller now always has tenant extension
Ensures WorkerPoller follows same pattern as MemoryEngine - always
creates a DefaultTenantExtension if none is provided, preventing
NoneType errors when calling list_tenants().
Fixes test failures in test_worker.py
* fix: DefaultTenantExtension honors explicit schema parameter
Allows WorkerPoller's schema parameter to be passed through to
DefaultTenantExtension via config dict, maintaining backward
compatibility for tests that use schema parameter without
providing a tenant extension.
Fixes test_poller_with_custom_schema test failure.
