Refactor transport calculation into shared domain

tests/test_calculation_api.py

@@ -2,6 +2,7 @@ import base64
 import os
 import tempfile
 import unittest
+from unittest.mock import patch
 
 import app as rollcalc_app
 
@@ -62,6 +63,42 @@ class CalculationApiTests(unittest.TestCase):
         self.assertEqual(result["state"]["request"]["roll_length_m"], 80.0)
         self.assertEqual(result["calculation"]["effective_roll_length_m"], 80.0)
 
+    def test_transport_endpoint_delegates_to_shared_domain_service(self):
+        payload = {
+            "length_m": 10,
+            "width_m": 5,
+            "height_m": 5,
+            "max_weight_kg": 10000,
+            "roll_diameter_mm": 1000,
+            "core_diameter_mm": 150,
+            "roll_width_m": 1,
+            "roll_weight_kg": 1000,
+        }
+        with patch.object(
+            rollcalc_app,
+            "analyze_transport",
+            return_value={"status": "success", "analysis": {"final_rolls": 10}},
+        ) as analyze:
+            response = self.client.post(
+                "/api/calculations/transport",
+                json=payload,
+                headers=self.headers,
+            )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.get_json()["analysis"]["final_rolls"], 10)
+        analyze.assert_called_once_with(payload)
+
+    def test_transport_endpoint_returns_structured_domain_validation(self):
+        response = self.client.post(
+            "/api/calculations/transport",
+            json={"length_m": 0},
+            headers=self.headers,
+        )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.get_json()["status"], "invalid_parameter")
+
 
 if __name__ == "__main__":
     unittest.main()