Refactor transport calculation into shared domain

tests/test_roll_calculation.py

@@ -8,6 +8,7 @@ from roll_calculation import (
     CalculationState,
     _canonical_name,
     calculate_roll,
+    get_article,
     modify_calculation,
 )
 
@@ -90,6 +91,35 @@ class RollCalculationTests(unittest.TestCase):
     def calculate_fixture(self, payload):
         return calculate_roll(payload, article_repository=self.repository)
 
+    def test_public_get_article_uses_repository_resolution_and_projection(self):
+        result = get_article("00123", article_repository=self.repository)
+
+        self.assertEqual(result["status"], "resolved")
+        self.assertEqual(result["article"]["number"], "00123")
+        self.assertEqual(result["article"]["width_m"], 4.9)
+        self.assertEqual(result["article"]["area_weight_g_m2"], 1000.0)
+
+    def test_public_get_article_preserves_not_found_ambiguous_and_conflict_results(self):
+        self.assertEqual(
+            get_article("does-not-exist", article_repository=self.repository)["status"],
+            "article_not_found",
+        )
+        self.assertEqual(
+            get_article(
+                article_name_hint="Duplicated Product",
+                article_repository=self.repository,
+            )["status"],
+            "article_ambiguous",
+        )
+        self.assertEqual(
+            get_article(
+                "00123",
+                "Other product",
+                article_repository=self.repository,
+            )["status"],
+            "article_conflict",
+        )
+
     def test_headless_matches_representative_existing_ui_values(self):
         result = calculate_roll(representative_request())
         calculation = result["calculation"]