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_currency_workflow.py

@@ -41,9 +41,10 @@ def test_create_capex_with_currency_code_and_list(api_client, seeded_currency):
     resp = api_client.post("/api/costs/capex", json=payload)
     assert resp.status_code == 200
     data = resp.json()
-    assert data.get("currency_code") == seeded_currency.code or data.get(
-        "currency", {}
-    ).get("code") == seeded_currency.code
+    assert (
+        data.get("currency_code") == seeded_currency.code
+        or data.get("currency", {}).get("code") == seeded_currency.code
+    )
 
 
 def test_create_opex_with_currency_id(api_client, seeded_currency):