fix(tests): correct ZIP4Data field names in E2E test

The test was checking for non-existent fields:
- zip4.zip4 → zip4.plus4
- zip4.delivery_point → zip4.city_delivery

Also added validation for zip9 and valid_delivery_area fields
to match the actual API response structure.

Verified with real API - test now passes.

Author: sylvesterdamgaard

tests/e2e/test_api.py

@@ -460,9 +460,11 @@ def test_integration_with_zip4(client):
 
     # Check ZIP+4 data
     if fields.zip4:
-        assert fields.zip4.zip4 is not None
-        assert fields.zip4.delivery_point is not None
+        assert fields.zip4.plus4 is not None
+        assert fields.zip4.zip9 is not None
         assert fields.zip4.carrier_route is not None
+        assert fields.zip4.city_delivery is not None
+        assert fields.zip4.valid_delivery_area is not None
 
 
 def test_integration_with_ffiec(client):