Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

tests/unit/test_maintenance.py

@@ -30,7 +30,9 @@ def _create_scenario_and_equipment(client: TestClient):
     return scenario_id, equipment_id
 
 
-def _create_maintenance_payload(equipment_id: int, scenario_id: int, description: str):
+def _create_maintenance_payload(
+    equipment_id: int, scenario_id: int, description: str
+):
     return {
         "equipment_id": equipment_id,
         "scenario_id": scenario_id,
@@ -43,7 +45,8 @@ def _create_maintenance_payload(equipment_id: int, scenario_id: int, description
 def test_create_and_list_maintenance(client: TestClient):
     scenario_id, equipment_id = _create_scenario_and_equipment(client)
     payload = _create_maintenance_payload(
-        equipment_id, scenario_id, "Create maintenance")
+        equipment_id, scenario_id, "Create maintenance"
+    )
 
     response = client.post("/api/maintenance/", json=payload)
     assert response.status_code == 201
@@ -95,7 +98,8 @@ def test_update_maintenance(client: TestClient):
     }
 
     response = client.put(
-        f"/api/maintenance/{maintenance_id}", json=update_payload)
+        f"/api/maintenance/{maintenance_id}", json=update_payload
+    )
     assert response.status_code == 200
     updated = response.json()
     assert updated["maintenance_date"] == "2025-11-01"
@@ -108,7 +112,8 @@ def test_delete_maintenance(client: TestClient):
     create_response = client.post(
         "/api/maintenance/",
         json=_create_maintenance_payload(
-            equipment_id, scenario_id, "Delete maintenance"),
+            equipment_id, scenario_id, "Delete maintenance"
+        ),
     )
     assert create_response.status_code == 201
     maintenance_id = create_response.json()["id"]