fix: unify error response format with error_code, message and domain fields

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_location_api.py

@@ -14,7 +14,7 @@ def test_register_location_success(client: TestClient):
 
 
 def test_register_location_duplicate(client: TestClient):
-    """重复上架 — 应返回 409"""
+    """重复上架 — 应返回 409，包含统一错误格式"""
     client.post(
         "/CargoTrace/location",
         json={"zongpai_no": "26C999", "location_code": "A01-02-03"},
@@ -25,26 +25,29 @@ def test_register_location_duplicate(client: TestClient):
     )
     assert resp.status_code == 409
     data = resp.json()
-    assert data["detail"]["error_code"] == "DUPLICATE_LOCATION"
-    assert "existing_location" in data["detail"]["detail"]
+    assert data["error_code"] == "DUPLICATE_LOCATION"
+    assert data["location_code"] == "A01-02-03"
+    assert "registered_at" in data
 
 
 def test_register_location_invalid_zongpai(client: TestClient):
-    """无效总排号 — 应返回 422"""
+    """无效总排号 — 应返回 400"""
     resp = client.post(
         "/CargoTrace/location",
         json={"zongpai_no": "INVALID", "location_code": "A01-02-03"},
     )
-    assert resp.status_code == 422
+    assert resp.status_code == 400
+    assert resp.json()["error_code"] == "INVALID_ZONGPAI"
 
 
 def test_register_location_invalid_location(client: TestClient):
-    """无效货位号 — 应返回 422"""
+    """无效货位号 — 应返回 400"""
     resp = client.post(
         "/CargoTrace/location",
         json={"zongpai_no": "26T999", "location_code": "bad-location"},
     )
-    assert resp.status_code == 422
+    assert resp.status_code == 400
+    assert resp.json()["error_code"] == "INVALID_LOCATION"
 
 
 def test_register_location_trans_location(client: TestClient):