fix: resolve remaining Inventory.location test failures and add Grafana config fields

- Fix test_inventory_service.py: replace model .location with .bin_location
- Fix test_product_model.py: remove location= from Inventory constructors
- Add grafana_admin_user/password to Settings for production Grafana config

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

app/modules/catalog/tests/unit/test_product_model.py

@@ -324,7 +324,6 @@ class TestProductInventoryProperties:
             store_id=test_store.id,
             warehouse="strassen",
             bin_location="SA-01-01",
-            location="WAREHOUSE_A",
             quantity=100,
             reserved_quantity=10,
         )
@@ -333,7 +332,6 @@ class TestProductInventoryProperties:
             store_id=test_store.id,
             warehouse="strassen",
             bin_location="SA-01-02",
-            location="WAREHOUSE_B",
             quantity=50,
             reserved_quantity=5,
         )
@@ -382,7 +380,6 @@ class TestProductInventoryProperties:
             store_id=test_store.id,
             warehouse="strassen",
             bin_location="DIG-01-01",
-            location="DIGITAL_LICENSES",
             quantity=10,
             reserved_quantity=2,
         )