Address district breakdown PR review notes

Author: anth-volk

policyengine_api/openapi_spec.yaml

@@ -773,6 +773,14 @@ paths:
           required: false
           schema:
             type: string
+        - name: include_district_breakdowns
+          in: query
+          description: Deprecated no-op. Congressional district results are returned automatically for US national and state-level simulations.
+          deprecated: true
+          required: false
+          schema:
+            type: boolean
+            default: false
       responses:
         200:
           description: Calculating economic impact.

tests/unit/routes/test_economy_dataset_validation.py

@@ -54,6 +54,7 @@ def test_economy_route_ignores_deprecated_breakdown_flag(mock_get_economic_impac
 
     assert response.status_code == 200
     assert payload["status"] == "ok"
+    assert payload["result"]["congressional_district_impact"] == {"districts": []}
     mock_get_economic_impact.assert_called_once()
     assert mock_get_economic_impact.call_args.kwargs["dataset"] == "default"
     assert mock_get_economic_impact.call_args.kwargs["options"] == {}