fix(tests): login als Helper-Funktion statt Fixture importieren (CI-Fix FOUND-007)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CVgbozhYmuEhiEJHffRXCV

backend/tests/test_import_export.py

@@ -1,10 +1,10 @@
-import io
-
 import pytest
 
+from tests.conftest import login
+
 
 @pytest.mark.asyncio
-async def test_objekte_export_import_roundtrip(client, admin_user, login, standort_factory, objekt_factory):
+async def test_objekte_export_import_roundtrip(client, admin_user, standort_factory, objekt_factory):
     standort = await standort_factory("Wache-Export")
     await objekt_factory(name="Rucksack A", code="RS-EXP-1", standort=standort)
     token = await login(client, "admin1")
@@ -24,7 +24,7 @@ async def test_objekte_export_import_roundtrip(client, admin_user, login, stando
 
 
 @pytest.mark.asyncio
-async def test_objekte_import_neue_zeile_mit_fehler(client, admin_user, standort_factory, login):
+async def test_objekte_import_neue_zeile_mit_fehler(client, admin_user, standort_factory):
     standort = await standort_factory("Wache-Import")
     token = await login(client, "admin1")
     header = {"Authorization": f"Bearer {token}"}
@@ -44,7 +44,7 @@ async def test_objekte_import_neue_zeile_mit_fehler(client, admin_user, standort
 
 @pytest.mark.asyncio
 async def test_geraete_export_import_roundtrip(
-    client, admin_user, login, standort_factory, objekt_factory, material_factory, db_session
+    client, admin_user, standort_factory, objekt_factory, material_factory, db_session
 ):
     from app.models.objektposition import Objektposition
     from decimal import Decimal