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.

routes/currencies.py

@@ -97,20 +97,20 @@ def _ensure_default_currency(db: Session) -> Currency:
 def _get_currency_or_404(db: Session, code: str) -> Currency:
     normalized = code.strip().upper()
     currency = (
-        db.query(Currency)
-        .filter(Currency.code == normalized)
-        .one_or_none()
+        db.query(Currency).filter(Currency.code == normalized).one_or_none()
     )
     if currency is None:
         raise HTTPException(
-            status_code=status.HTTP_404_NOT_FOUND, detail="Currency not found")
+            status_code=status.HTTP_404_NOT_FOUND, detail="Currency not found"
+        )
     return currency
 
 
 @router.get("/", response_model=List[CurrencyRead])
 def list_currencies(
     include_inactive: bool = Query(
-        False, description="Include inactive currencies"),
+        False, description="Include inactive currencies"
+    ),
     db: Session = Depends(get_db),
 ):
     _ensure_default_currency(db)
@@ -121,14 +121,12 @@ def list_currencies(
     return currencies
 
 
-@router.post("/", response_model=CurrencyRead, status_code=status.HTTP_201_CREATED)
+@router.post(
+    "/", response_model=CurrencyRead, status_code=status.HTTP_201_CREATED
+)
 def create_currency(payload: CurrencyCreate, db: Session = Depends(get_db)):
     code = payload.code
-    existing = (
-        db.query(Currency)
-        .filter(Currency.code == code)
-        .one_or_none()
-    )
+    existing = db.query(Currency).filter(Currency.code == code).one_or_none()
     if existing is not None:
         raise HTTPException(
             status_code=status.HTTP_409_CONFLICT,
@@ -148,7 +146,9 @@ def create_currency(payload: CurrencyCreate, db: Session = Depends(get_db)):
 
 
 @router.put("/{code}", response_model=CurrencyRead)
-def update_currency(code: str, payload: CurrencyUpdate, db: Session = Depends(get_db)):
+def update_currency(
+    code: str, payload: CurrencyUpdate, db: Session = Depends(get_db)
+):
     currency = _get_currency_or_404(db, code)
 
     if payload.name is not None:
@@ -175,7 +175,9 @@ def update_currency(code: str, payload: CurrencyUpdate, db: Session = Depends(ge
 
 
 @router.patch("/{code}/activation", response_model=CurrencyRead)
-def toggle_currency_activation(code: str, body: CurrencyActivation, db: Session = Depends(get_db)):
+def toggle_currency_activation(
+    code: str, body: CurrencyActivation, db: Session = Depends(get_db)
+):
     currency = _get_currency_or_404(db, code)
     code_value = getattr(currency, "code")
     if code_value == DEFAULT_CURRENCY_CODE and body.is_active is False: