Refactor codebase following Clean Code principles and add 229 tests

- Extract helpers to reduce function sizes (listing_tasks, app.py, query.py, listing_fetcher)
  - Replace nonlocal mutations with _PipelineState dataclass in listing_tasks
  - Fix bugs: isinstance→equality check in repository, verify_exp for OIDC tokens
  - Consolidate duplicate filter methods in listing_repository
  - Move hardcoded config to env vars with backward-compatible defaults
  - Simplify CLI decorator to auto-build QueryParameters
  - Add deprecation docstring to data_access.py
  - Test count: 158 → 387 (all passing)

crawler/tests/test_listing_geojson.py

@@ -97,7 +97,7 @@ class TestListingGeoJsonEndpoint:
 
         # Override auth dependency
         async def mock_auth():
-            return User(email="test@example.com", name="Test User")
+            return User(sub="test-id", email="test@example.com", name="Test User")
 
         app.dependency_overrides[get_current_user] = mock_auth
         yield TestClient(app)