refactor(exercises): standardize answer language handling across exercise scripts

- Introduced a mechanism to infer answer language based on question phrasing in multiple exercise scripts, enhancing consistency in exercise data.
- Updated question formats to clarify the intent of exercises, improving user understanding and engagement.
- Streamlined the code for better maintainability and clarity in exercise generation processes.

backend/scripts/update-food-care-exercises.js

@@ -582,6 +582,7 @@ async function updateFoodCareExercises() {
             instruction: 'Wähle die richtige Übersetzung.',
             questionData: JSON.stringify({
               type: 'multiple_choice',
+              answerLanguage: 'target',
               question: `Wie sagt man "${conv.native}" auf Bisaya?`,
               options: [
                 conv.bisaya,
@@ -608,6 +609,7 @@ async function updateFoodCareExercises() {
             instruction: 'Wähle die richtige Übersetzung.',
             questionData: JSON.stringify({
               type: 'multiple_choice',
+              answerLanguage: 'native',
               question: `Was bedeutet "${conv.bisaya}"?`,
               options: [
                 conv.native,