feat: initialize state for image URL in WriteRecipePage component

frontend/app/recipes/write/WriteRecipePage.tsx

@@ -43,6 +43,7 @@ export default function WriteRecipePage() {
   const [editedName, setEditedName] = useState('');
   const [editedDescription, setEditedDescription] = useState('');
   const [editedInstructions, setEditedInstructions] = useState('');
+  const [imageUrl, setImageUrl] = useState<string | null>(null);
   const [ingredients, setIngredients] = useState<ParsedIngredientRow[]>([]);
   const [allProducts, setAllProducts] = useState<Product[]>([]);
   const [isParsing, setIsParsing] = useState(false);